7 - 11 April 2024
Strasbourg, France
Organic materials are interesting for a myriad of photonic and optoelectronic applications due to their tunability of key electronic and optical properties, their versatility of processing, the softness of the solid films formed, and their potential to allow for non-toxic materials. Currently monochrome organic light-emitting diodes are a commercial product used in displays, while organic photovoltaics and sensors for low cost, bio, artificial skin, or wearable applications have seen rapid development in recent years. Based on this very versatile material platform, it is expected that many other innovative application concepts will be discovered and developed. Hereby does fundamental research on organic electronics and photonics form the backbone for the discovery of new applications, especially, when properties of materials are evaluated free of pre-determined applications. Moreover, basic experimental and theoretical research on charge, energy, and spin transfer processes, organic-organic interfaces and their electronic structure, will provide structure-property relations and progress existing applications.

The focus of this conference will be on the following topics: ;
In progress – view active session
Conference 13013

Organic Electronics and Photonics: Fundamentals and Devices IV

9 - 11 April 2024 | Berlin/Salon 9, Niveau/Level 0
View Session ∨
  • 1: Organic Light-emitting Diodes I
  • 2: Organic Transistors
  • 3: Organic Luminescence I
  • Hot Topics II
  • 4: New Devices and Phenomena
  • 5: Organic Photovoltaics I
  • 6: Organic Light-emitting Diodes II
  • 7: Organic Luminescence II
  • Posters-Wednesday
  • Hot Topics III
  • 8: Organic Photovoltaics II
  • 9: New Materials, Concepts, and Devices I
  • 10: New Materials, Concepts, and Devices II
Session 1: Organic Light-emitting Diodes I
9 April 2024 • 08:40 - 10:10 CEST | Berlin/Salon 9, Niveau/Level 0
Session Chair: Sebastian Schellhammer, TU Dresden (Germany)
Author(s): Francisco Tenopala Carmona, Dirk Hertel, Sabina G. H. Hillebrandt, Andreas Mischok, Univ. zu Köln (Germany); Arko Graf, Univ. of St. Andrews (United Kingdom); Philipp Weitkamp, Klaus Meerholz, Malte C. Gather, Univ. zu Köln (Germany)
9 April 2024 • 08:40 - 09:10 CEST | Berlin/Salon 9, Niveau/Level 0
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The outcoupling efficiency of OLEDs can be significantly enhanced by orienting the emitter molecules horizontally within the film. While some guidelines have been developed to control molecular orientation in OLEDs[1], our understanding of the factors at play remains limited by the fact that current techniques only obtain average values of what in reality is a distribution of orientations. Here, we develop a method to obtain orientation distributions of emitters in thermally evaporated films of host-guest emissive layers relevant to OLED displays[2]. We achieve this by adapting out-of-focus fluorescence imaging of individual molecules for use in thermally evaporated systems. We show how the orientation distribution of emitters depends on processing conditions and on the nanoscale environment of the emitters. Crucially, we also show that emitters can adopt different orientation distributions that would be indistinguishable in ensemble-averaging measurements. [1] F. Tenopala-Carmona, … M. C. Gather, Adv. Mater. 2021, 33, 2100677 [2] F. Tenopala-Carmona, … M. C. Gather, Nat. Comm. 2023, 14, 6126
Author(s): Fiorita Nunziata, Univ. degli Studi di Salerno (Italy), MATERIAS s.r.l (Italy); Salvatore Aprano, ENEA (Italy); Rosalba Liguori, Univ. degli Studi di Salerno (Italy); Maria Grazia Maglione, Paolo Tassini, ENEA (Italy); Alfredo Rubino, Univ. degli Studi di Salerno (Italy)
9 April 2024 • 09:10 - 09:30 CEST | Berlin/Salon 9, Niveau/Level 0
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Organic Light Emitting Diodes (OLEDs) represent a cutting-edge lighting technology, offering the possibility of transparent light sources. Transparent OLEDs can be integrated into glass windows, panels, and lamps, transforming these surfaces into lighting objects that, when turned off, let natural light pass through. However, achieving high performance involves the challenge of finding transparent electrodes with superior electro-optical properties. While transparent conducting oxides deposited by sputtering are commonly used for bottom electrodes, this process is unsuitable for top electrodes due to the potential damage to underlying organic layers caused by high-energy particle plasma emission. This study investigates the impact of Indium Tin Oxide (ITO) deposition on OLED active layer, aiming to balance process conditions and ITO film electro-optical properties, minimizing sputtering-induced damage. It also explores the benefits of a thin thermally evaporated calcium layer before ITO sputtering, serving as both a protective layer and a good electron injector for OLEDs.
Author(s): Konstantinos Daskalakis, Univ. of Turku (Finland)
9 April 2024 • 09:30 - 09:50 CEST | Berlin/Salon 9, Niveau/Level 0
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In this presentation, I discuss our recent study investigating the influence of strong coupling in polariton organic light-emitting diodes using time-resolved electroluminescence studies [1]. We fabricated bottom-emitting polariton OLEDs, employing the well-established polariton TDAF molecular semiconductor between aluminum electrodes. Our analysis, based on a model of coupled rate equations, considered all major mechanisms contributing to delayed electroluminescence in organic emitters. We found that in our devices emission dynamics remained unmodified in the presence of strong coupling. I will also discuss the prospects of strong coupling and photonics as an alternative route to investigate material properties that are usually inaccessible. This direction may offer new avenues for OLEDs to benefit from polaritonic research [2]. [1] A. G. Abdelmagid, H. A. Qureshi, M. A. Papachatzakis, O. Siltanen, M. Kumar, A. Ashokan, S. Salman, K. Luoma, and K. S. Daskalakis, arXiv:2309.12737, (2023). [2] E. Palo, M. A. Papachatzakis, A. Abdelmagid, H. Qureshi, M. Kumar, M. Salomaki, and K. S. Daskalakis, The Journal of Physical Chemistry C 127, 14255, 2023.
Author(s): Houssein El Housseiny, Ghada Mbarki, David Buso, Marc E. Ternisien, Georges Zissis, Cédric Renaud, Lab. Plasma et Conversion d'Energie (France)
9 April 2024 • 09:50 - 10:10 CEST | Berlin/Salon 9, Niveau/Level 0
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Exciplex are generated at the heterojunction interface of electron donor and acceptor materials. Exciplex strategy can, thus, reduce molecular design difficulties for obtaining near-UV emission by selecting the appropriate electron donors and acceptors. Induced exciplex of Tris(4-carbazoyl-9-ylphenyl)amine (TCTA)/ 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) were applied to design deep blue organic light emitting diodes (OLEDs). BCP was used as an electron transport material and TCTA as a hole transporting material. The investigations carried out on planar-heterojunction have shown that recombination region was located at the vicinity of TCTA/BCP interface leading to exciplex formation. Furthermore, the thicknesses of BCP and TCTA layers play a key role in the control of the recombination zone and the emission color of the OLEDs. The electroluminescent spectra of planar-heterojunction exciplex-based OLEDs displayed deep blue emission at 423 nm with CIE coordinate of (0.16, 0.11). The emission of bulk-heterojunction exciplex-based OLEDs are also investigated showing that their emission is dominated by electroplex emission.
Coffee Break 10:10 - 10:40
Session 2: Organic Transistors
9 April 2024 • 10:40 - 12:30 CEST | Berlin/Salon 9, Niveau/Level 0
Session Chair: Wouter Maes, Univ. Hasselt (Belgium)
Author(s): Stefania Moro, Giovanni Costantini, Univ. of Birmingham (United Kingdom)
9 April 2024 • 10:40 - 11:10 CEST | Berlin/Salon 9, Niveau/Level 0
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Conjugated polymers (CPs) hold promise for modern organic electronics due to their adaptability and cost-effectiveness. However, their molecular-scale characterization is still challenging. In this talk, I will show how the high-resolution imaging capabilities of scanning tunnelling microscopy (STM) can be used to analyse CPs and surpass conventional analytical limits. With a series of examples, I will demonstrate that this method allows molecule-by-molecule characterisation, revealing self-assembly, length distribution, sequence, and chemical structure of the polymers. These can be used to investigate microscale behaviour, comparing polymerization techniques, understanding side-chain effects, and fully characterise CPs where traditional methods fall short, due to aggregation or mass limitations.
Author(s): Lize Bynens, Jochen Vanderspikken, Univ. Hasselt (Belgium); Adam Marks, Stanford Univ. (United States); Arwin Goossens, Univ. Hasselt (Belgium); Tyler J. Quill, Garret Lecroy, Christina Cheng, Yeongmin Park, Stanford Univ. (United States); Laurence Lutsen, Univ. Hasselt (Belgium); Alberto Salleo, Stanford Univ. (United States); Koen Vandewal, Wouter Maes, Univ. Hasselt (Belgium)
9 April 2024 • 11:10 - 11:30 CEST | Berlin/Salon 9, Niveau/Level 0
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State-of-the-art alternating semiconducting polymers, synthesized via established academic protocols, often contain homocoupling defects, causing the true structure to deviate from the anticipated perfectly alternating polymer backbone. These structural defects significantly hinder the reproducibility across different polymer batches, posing a challenge to the commercial viability of the organic semiconductor field, while simultaneously imposing performance limitations in different applications by creating defected chains, limiting the attainable molecular weight and increasing the dispersity. In this study, two synthesis methods – conventional Stille polymerization and a novel defect-free route – are employed to create the p-type accumulation mode OECT (organic electrochemical transistor) benchmark material pgBTTT. The effect of homocoupling, and its absence, is investigated by comparing the bulk properties of the two polymers and evaluating their respective OECT performances.
Author(s): Julien Réhault, Priscila Cavassin, Isabelle Holzer, Natalie Banerji, Univ. Bern (Switzerland); Christian B. Nielsen, Raymundo Marcial Hernandez, Queen Mary Univ. of London (United Kingdom); Peter Gilhooly-Finn, Univ. College London (United Kingdom)
9 April 2024 • 11:30 - 11:50 CEST | Berlin/Salon 9, Niveau/Level 0
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In this contribution, we will present different spectroscopic methods used to investigate organic mixed ionic-electronic conductors (OMIECs) which constitute a promising material class for interfacing biological systems with electronics. Organic electrochemical transistors (OECTs) are a solution for this task and are often used to benchmark OMIECs performance. Different studies have showed that polymers designed with hydrophilic solubilizing chains show better OECT performance, mostly due to their higher ionic uptake and stability in aqueous environments. We explore how side chain engineering in poly(3-hexylthiophene) (P3HT) with different content of TriEthylene Glycol (TEG) impacts its electronic and ionic transport properties.
Author(s): Kaishuai Zhang, Univ. Bern (Switzerland); Lize Bynens, Univ. Hasselt (Belgium)
9 April 2024 • 11:50 - 12:10 CEST | Berlin/Salon 9, Niveau/Level 0
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This study explores the impact of ethylene glycol side chain modification in pgBTTT polymers, a key component in organic electrochemical transistors. By varying the concentration of these side chains from 50% to 100%, we observed a significant influence on the polymers' volumetric capacitance, with an interesting deviation at 90% concentration. Additionally, we investigated the efficacy of blending techniques to enhance this capacitance. Two blending approaches were tested: pgBTTT with pBTTT (OR)2 and pgBTTT with pgBTTT-OEG-OR. These blends demonstrated superior volumetric capacitance compared to copolymers, especially at higher side chain ratios. Importantly, blends with matching side chain ratios exhibited improved kinetics in doping and dedoping processes. These findings offer valuable insights for optimizing the structure and performance of organic electrochemical devices, paving the way for more efficient and effective electrochemical transistors and mixed conductors.
Author(s): Katelyn P. Goetz, Adam J. Biacchi, Chad D. Cruz, Sebastian Engmann, Curt A. Richter, Chad R. Snyder, Emily G. Bittle, National Institute of Standards and Technology (United States)
9 April 2024 • 12:10 - 12:30 CEST | Berlin/Salon 9, Niveau/Level 0
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The use of singlet fission to enhance device efficiency or enable new capabilities raises the need to investigate it on a slow operational timescale. Using a transistor-based measurement to examine temperature-dependent singlet fission in tetracene single crystals, we observe that it is activated to 210 K, at which point it undergoes an optoelectronic phase transition. We compare these results to those of pentacene and suggest that the phase change is due to a change in the singlet fission kinetics. We further examine the interplay between this readout and other extrinsic and intrinsic device properties, such as disorder and trap states. Our results give insight not only into the readout mechanism of this OFET-based measurement, but also strategies to manipulate and tune the response.
Lunch/Exhibition Break 12:30 - 14:00
Session 3: Organic Luminescence I
9 April 2024 • 14:00 - 15:50 CEST | Berlin/Salon 9, Niveau/Level 0
Session Chair: Koen Vandewal, Univ. Hasselt (Belgium)
Author(s): Madalasa Mondal, Ratheesh K. Vijayaraghavan, Indian Institute of Science Education and Research Kolkata (India)
9 April 2024 • 14:00 - 14:20 CEST | Berlin/Salon 9, Niveau/Level 0
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We have presented findings on TADF emitters consisting of a strong D-A structure, exhibiting hybridized electronic excited states that encompass a primary donor-to-acceptor long-range (LR) interaction and an ancillary short-range (SR) charge-transfer characteristic. This configuration successfully balances a small ΔEST and a large f value. Our thorough theoretical and experimental analysis has uncovered that the addition of peripheral donor units to the core D-A backbone leads to the formation of multiple triplet excited states between the S1 and T1 states, exhibiting locally excited or hybridized characteristics. The close alignment of the 1CT and 3LE states accelerates the spin-flip process, resulting in a sizable radiative rate nearly equivalent to the intersystem crossing (ISC) rate. Additionally, a decent reverse ISC rate (107 s-1) is simultaneously obtained in one emitter, leading to a short (ns) delayed lifetime and effectively suppressing efficiency roll-off.
Author(s): Kikuya Hayashi, Shuzo Hirata, The Univ. of Electro-Communications (Japan)
9 April 2024 • 14:20 - 14:40 CEST | Berlin/Salon 9, Niveau/Level 0
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Afterglow emission allows for imaging that is independent of autofluorescence under ambient conditions. Although higher-resolution afterglow is required for increasing the quality of the autofluorescence-free emission imaging, increasing the excitation intensity to generate brighter afterglow emission decreases the resolution of afterglow images. Therefore, methods and materials that provide afterglow imaging with higher resolution remain to be developed. In this study, we performed photoinduced triplet depletion and demonstrated improved resolution of bright afterglow emission using the depletion. Triplet depletion is related to charge separation via photoionization from a triplet state caused by the depletion and subsequent rapid singlet formation. Triplet excitons that accumulated in a solid material by excitation were depleted under irradiation using a depletion beam with a longer wavelength than the absorption wavelength of the material. A higher-resolution afterglow image with an improvement of 25% was obtained by simultaneously focusing a donut-shaped depletion beam and an excitation beam.
Author(s): Bernhard Siegmund, Sigurd Mertens, Koen Vandewal, Univ. Hasselt (Belgium)
9 April 2024 • 14:40 - 15:00 CEST | Berlin/Salon 9, Niveau/Level 0
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Luminescent solar concentrators (LSC) are an attractive emerging concept for semi-transparent, building-integrated photovoltaics at low cost and weight. Hereby, large-area, luminescent wave-guide foils collect solar radiation, being harvested at the wave-guide’s edge by a small-size solar module. To further improve the performance of LSCs, emitter materials with photoluminescence quantum yields (PLQY) near-unity are required, as this minimizes losses due to photon re-absorption events. This presentation show-cases a highly sensitive approach to experimentally determine the PLQY of emitters, combining spectroscopic and photothermal techniques. Screening the PLQY of six emitter molecules in solution, we are able to measure a maximum value of 99.4% with an unprecedented precision down to ±0.3% – which is about ten times better than established techniques. This newly developed method will therefore contribute to the development of future highly efficient LSCs, which require emitters with extremely high PLQYs, well above 99%. We further show that such emitters can perform thermally assisted photon upconversion, illustrating their potential for optical refrigeration.
Author(s): Sebastian Schellhammer, Heidi Thomas, Tim Achenbach, Sebastian Kaiser, Sebastian Reineke, TU Dresden (Germany)
9 April 2024 • 15:00 - 15:20 CEST | Berlin/Salon 9, Niveau/Level 0
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We present a design for programmable luminescent tags fully made from biodegradable, ready-to-use materials (bioPLTs) allowing for waste-free information storage. Quinine embedded in polylactic acid as host material provides sufficient room temperature phosphorescence (RTP) for easy readout even under continuous-wave illumination. Exceval is used as oxygen blocking layer to locally control the oxygen-sensitive RTP emission for high-resolution writing of information. Accordingly, these bioPLTs exhibit all function-defining characteristics also found in their regular non-biodegradable analogs even including a flexible design when using polylactic acid foils as substrate.
Author(s): Shuzo Hirata, The Univ. of Electro-Communications (Japan)
9 April 2024 • 15:20 - 15:50 CEST | Berlin/Salon 9, Niveau/Level 0
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The persistent emission that remains after excitation light irradiation is stopped enables high-contrast imaging without relying on surrounding autofluorescence. However, the luminance of common persistent emitting materials hardly increases even when the excitation light intensity increases. Therefore, persistent emission has not been utilized for high-resolution imaging. Here we introduce approaches to obtain high-resolution afterglow information using persistent room temperature phosphorescence (RTP). In order to obtain the high-resolution afterglow information, it is necessary to improve the RTP yield and suppress the saturation of RTP brightness under strong light excitation. We explain the molecular designs to enhance the RTP yield using unique dynamic quantum chemical calculations. For the suppression of the RTP brightness with excitation irradiance, Forster resonance energy transfer to the accumulated triplet excitons in strong excitation is discussed. Finally, afterglow emission from the individual nanoparticles of materials showing bright persistent RTP was demonstrated in an atmospheric and aqueous solution environment.
Coffee Break 15:50 - 16:30
Hot Topics II
9 April 2024 • 16:30 - 18:05 CEST | Auditorium Schweitzer, Niveau/Level 0
Session Moderator:
Anna Mignani, Istituto di Fisica Applicata "Nello Carrara" (Italy)
2024 Symposium Chair

16:30 hrs
Welcome and Opening Remarks
Speaker Introduction
Author(s): Kathy Lüdge, Technische Univ. Ilmenau (Germany)
9 April 2024 • 16:35 - 17:20 CEST | Auditorium Schweitzer, Niveau/Level 0
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Optical cavities with nonlinear elements and delayed self-coupling are widely explored candidates for photonic reservoir computing (RC). For time series prediction applications that appear in many real-world problems, energy efficiency, robustness and performance are key indicators. With this contribution I want to clarify the role of internal dynamic coupling and timescales on the performance of a photonic RC system and discuss routes for optimization. By numerically comparing various delay-based RC systems e.g., quantum-dot lasers, spin-VCSEL (vertically emitting semiconductor lasers), and semiconductor amplifiers regarding their performance on different time series prediction tasks, to messages are emphasized: First, a concise understanding of the nonlinear dynamic response (bifurcation structure) of the chosen dynamical system is necessary in order to use its full potential for RC and prevent operation with unsuitable parameters. Second, the input scheme (optical injection, current modulation etc.) crucially changes the outcome as it changes the direction of the perturbation and therewith the nonlinearity. The input can be further utilized to externally add a memory timescale that is needed for the chosen task and thus offers an easy tunability of RC systems.
Author(s): José Capmany Francoy, Univ. Politècnica de València (Spain)
9 April 2024 • 17:20 - 18:05 CEST | Auditorium Schweitzer, Niveau/Level 0
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Programmable photonic circuits manipulate the flow of light on a chip by electrically controlling a set of tunable analog gates connected by optical waveguides. Light is distributed and spatially rerouted to implement various linear functions by interfering signals along different paths. A general-purpose photonic processor can be built by integrating this flexible hardware in a technology stack comprising an electronic monitoring and controlling layer and a software layer for resource control and programming. This processor can leverage the unique properties of photonics in terms of ultra-high bandwidth, high-speed operation, and low power consumption while operating in a complementary and synergistic way with electronic processors. This talk will review the recent advances in the field and it will also delve into the potential application fields for this technology including, communications, 6G systems, interconnections, switching for data centers and computing.
Session 4: New Devices and Phenomena
10 April 2024 • 08:50 - 10:30 CEST | Berlin/Salon 9, Niveau/Level 0
Session Chair: David Beljonne, Univ. de Mons (Belgium)
Author(s): Zhiyuan Kuang, Nanjing Tech Univ. (China)
10 April 2024 • 08:50 - 09:10 CEST | Berlin/Salon 9, Niveau/Level 0
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Zero-dimensional organic-inorganic metal halide (0D-OIMH) materials have demonstrated remarkable potential in diverse applications owing to their captivating optoelectronic character-istics. However, a dearth of comprehension exists regarding the exciton structure of these materials. In this study, we employ low temperature magneto-optical measurements to comprehensively investigate the excited state structure of a representative 0D-OIMH, namely (Bmpip)2SnBr4. The results reveal that the high-energy peak arises from bright excited states within a higher energy band, whilst, the low-energy peak originates from a combination of triplet bright states and singlet dark states. These findings falsify previous assignments of the two peaks, and provide profound insights into understanding the exciton structures of the distinctive 0D-OIMHs.
Author(s): Martin Bowen, Institut de Physique et de Chimie des Matériaux de Strasbourg (France)
10 April 2024 • 09:10 - 09:40 CEST | Berlin/Salon 9, Niveau/Level 0
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To enhance the singlet-to-triplet occupation ratio and boost radiative recombination in organic semiconductors, several schemes exist to inject charge carriers with a high degree of spin polarization. So far, the electrical current flowing across the ferromagnetic 3d metal/molecule interface has been shown to exhibit a maximum spin polarization P = 74% at 10K. Yet applications require a higher P and at room temperature, using a simple 3d metal. We will present magnetotransport results showing P=89% at T=40K across the Fe/C60 interface, and P=77% at 295K across the facile Co/C interface. These new records highlight the potential of this class of spin injectors for organic optoelectronics.
Author(s): Komlan Segbéya Gadedjisso-Tossou, Univ. Lomé (Togo); Jean-Michel Benoit, Clémentine Symonds, Joël Bellessa, Alban Gassenq, Univ. Claude Bernard Lyon 1 (France)
10 April 2024 • 09:40 - 10:00 CEST | Berlin/Salon 9, Niveau/Level 0
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Tetrachlorodiethyl Benzimidazo Carbocyanine (TDBC) layers are very interesting for photonics applications. They are used in strong coupling studies, wavelength selective grating fabrication, light concentration, absorption enhancement, etc.. However, their intrinsic properties are still not well understood, especially for the refractive index which presents some discrepancy in the literature. In this work, we have reviewed and investigated the refractive index of pure TDBC layers by ellipsometry and absorption measurements. We find that the fabrication and measurement methods can strongly affect the refractive index evaluation. Such work gives thus a better understanding of these promising layers for photonics applications.
Author(s): Sandrine Heutz, London Ctr. for Nanotechnology (United Kingdom)
10 April 2024 • 10:00 - 10:30 CEST | Berlin/Salon 9, Niveau/Level 0
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Spins in molecular films can be observed in the ground state in the form of free radials or paramagnetic ions. They can also be obtained in the photoexcited state, and harnessed to improve photoemission yields in OLEDs or efficiency in photovoltaics. One particularly intriguing phenomenon is singlet fission in pentacene, where a single photon absorbed for a singlet excitation can be converted into two triplets, potentially boosting efficiency in solar cells. This presentation will focus on elucidating the correlation between molecular structure and couplings of spins obtained by singlet photoexcitation. The impact of intermolecular interactions will be probed via pentacene dilution within an insulating matrix, and temperature-dependent spectroscopies including transient electron paramagnetic resonance. The impact of spin coupling on future applications will be considered.
Coffee Break 10:30 - 11:00
Session 5: Organic Photovoltaics I
10 April 2024 • 11:00 - 12:10 CEST | Berlin/Salon 9, Niveau/Level 0
Session Chair: Sylvain Chambon, Lab. d'Intégration du Matériau au Système (France)
CANCELED: Illuminating the dark side of triplet states (Invited Paper)
Author(s): Safa Shoaee, Paul-Drude-Institut für Festkörperelektronik (Germany)
10 April 2024 • 11:00 - 11:30 CEST | Berlin/Salon 9, Niveau/Level 0
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Optimization of the energy levels at the donor–acceptor interface of organic solar cells has driven their efficiencies to above 19%. However, further improvements towards efficiencies comparable with inorganic solar cells remain challenging because of high recombination losses, mediated by the lowest-energy (singlet and triplet) CT states, which empirically limit the open-circuit voltage (VOC). Using o-IDTBR blended with PM6, we achieve VOC of 1.16 V, associated with the achievement of remarkably low non-radiative recombination loss of 160 meV, despite presence of triplets. In employing the present system as a model exemplar, we elucidate the circumstance wherein, if the triplet lifetime surpasses that of the charge-transfer (CT) decay, the dissociation of triplet excitons to the CT state emerges as a feasible occurrence. This, in turn, serves to reduce the occurrence of an additional loss channel emanating from the T1 state.
Author(s): Kaat Valkeneers, Univ. Hasselt (Belgium); Quan Liu, Bernhard Siegmund, Laurence Lutsen, Koen Vandewal, Wouter Maes, IMO-IMOMEC, Univ. Hasselt (Belgium)
10 April 2024 • 11:30 - 11:50 CEST | Berlin/Salon 9, Niveau/Level 0
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Transparent photovoltaics, a burgeoning field at the intersection of materials science and renewable energy technology, have the potential to revolutionize the way in which we harness sunlight and integrate solar power into our daily lives. The performance of transparent photovoltaics is evaluated by the light utilization efficiency and necessitates a trade-off between optimizing efficiency and ensuring transparency. In this work, a comparative analysis is performed of two donor polymer materials that differ only in the presence of a single fluorine atom among the polymer backbone, examining their performance in transparent solar cells in relation to both of these critical aspects.
Author(s): Raitis Grzibovskis, Arturs Aizstrauts, Institute of Solid State Physics, Univ. of Latvia (Latvia); Armands Ruduss, Kaspars Traskovskis, Riga Technical Univ. (Latvia)
10 April 2024 • 11:50 - 12:10 CEST | Berlin/Salon 9, Niveau/Level 0
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In this work, we have studied the application of novel dicyanomethylene-functionalized s-indacene-tetraone based non-fullerene acceptors IC-1 and IC-2 as the third component in ternary organic solar cells (TOSCs). The chromophores IC-1 and IC-2 with donor-acceptor-donor (D-A-D) molecular composition were acquired by condensation reactions between s-indacene-tetraone derivative acceptor fragment and aniline- or indoline-based electron-donating fragments. Electron donor polymer PM6 and electron acceptor material Y7 were used as the base materials for the TOSCs. We show that the energy levels of IC-1 and IC-2 are located between the levels of PM6 and Y7 creating the cascade effect. IC-2 absorption has an additional shoulder between 650 nm and 800 nm which helps to increase the power conversion efficiency and reduce the losses shown by the external quantum efficiency (EQE) measurements.
Lunch/Exhibition Break 12:10 - 13:30
Session 6: Organic Light-emitting Diodes II
10 April 2024 • 13:30 - 15:00 CEST | Berlin/Salon 9, Niveau/Level 0
Session Chair: Malte C. Gather, Univ. zu Köln (Germany)
Author(s): Ludvig Edman, Umeå Univ. (Sweden)
10 April 2024 • 13:30 - 14:00 CEST | Berlin/Salon 9, Niveau/Level 0
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The light-emitting electrochemical cell (LEC) comprises mobile ions in the active material. It is the action of these ions that enables its attractive properties; notably, that complete LECs can be fabricated by scalable ambient-air printing and coating. The redistribution of the ions causes electrochemical doping of the emissive semiconductor (p-type at anode, n-type at cathode), which results in the formation of a p-n junction doping structure. This in-situ formed doping structure enables the printing fabrication, but also poses challenges from conceptual and performance perspectives. For instance, the doping regions comprise high concentration of mobile polarons that can cause severe exciton-polaron quenching, and the position of the emissive p-n junction for constructive interference cannot be controlled by conventional spatial design during device fabrication. Here, we present conceptual insights and rational design methods for alleviation of exciton-polaron quenching and for control of the position of the in-situ formed p-n junction for efficient emission. We also present developments towards an LEC, which is sustainable during both fabrication, operation and recycling.
Author(s): Rongjuan Huang, Sebastian Schellhammer, Sebastian Reineke, TU Dresden (Germany)
10 April 2024 • 14:00 - 14:20 CEST | Berlin/Salon 9, Niveau/Level 0
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Deep-red/near infrared (NIR) persistent emission from purely organic molecules possesses great potential for security protocols, imaging, and information exchange. Persistent electroluminescence, achieved by incorporating suitable materials in organic light-emitting diodes (OLEDs), is highly attractive as it allows to integrate the essential features into optoelectronic systems and applications. While first material systems using triplet-singlet Förster resonance energy transfer (TS-FRET) show promising characteristics, the concentrations of phosphorescent donor materials and fluorescent deep-red acceptor materials remain too low for OLED applications. In our contribution, we present a systematic photophysical analysis of several donor-acceptor combinations based on TS-FRET with the aim of increasing the donor concentration while keeping high photoluminescence quantum yields. Our results pave the way towards efficient deep-red/NIR down-conversion OLED pixels with persistent emission.
Author(s): Luis Paniagua Rodríguez, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany), Institut für Physik, Univ. Augsburg (Germany); Dirk Michaelis, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany); Christof Pflumm, Merck Electronics KGaA (Germany); Wolfgang Brütting, Institut für Physik, Univ. Augsburg (Germany); Norbert Danz, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany)
10 April 2024 • 14:20 - 14:40 CEST | Berlin/Salon 9, Niveau/Level 0
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A model for characterizing emission zone profiles (EMZ) in Organic LEDs is introduced. Considering limits for resolving EMZ features yields a characterization by two parameters only. This enables to compare different EMZ results numerically, to estimate confidence intervals for the experimental results, and to define optimization targets that can be observed experimentally. Exemplary data on current dependent EMZ shift will illustrate the application of the method.
Author(s): Hiroki Tomita, Peter A. Bobbert, Christ H. L. Weijtens, Reinder Coehoorn, Technische Univ. Eindhoven (Netherlands)
10 April 2024 • 14:40 - 15:00 CEST | Berlin/Salon 9, Niveau/Level 0
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Triplet-polaron quenching (TPQ) is one of the main causes of exciton loss in OLED devices, which seriously limits the luminance efficiency. In host-guest blend systems, which a phosphorescent “guest” emitter is diluted in a “host” material, the polarons can be located on a host or a guest molecule, and can be holes or electrons, dependent on the energy level structure. However, the mechanism of TPQ and the relation of the interaction strength with the molecular structure are not well known. Here, we present an integrated approach of experimental and simulation methods for obtaining TPQ interaction strength.
Coffee Break 15:00 - 15:30
Session 7: Organic Luminescence II
10 April 2024 • 15:30 - 17:40 CEST | Berlin/Salon 9, Niveau/Level 0
Session Chair: Koen Vandewal, Univ. Hasselt (Belgium)
Author(s): David Beljonne, Univ. de Mons (Belgium)
10 April 2024 • 15:30 - 16:00 CEST | Berlin/Salon 9, Niveau/Level 0
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We will report on state-of-the art, highly correlated wavefunction methods accounting for both static and dynamic electron correlation, aiming at the full characterization of the low-lying electronic excitations in (multi)chromophoric organic radicals. These methods have been applied to design organic molecules displaying both efficient luminescence and near-unity generation yield of high-spin multiplicity excited states. We will also present a host:guest design for OLEDs that exploits energy transfer with demonstration of up to 9.6% external quantum efficiency (EQE) for 800 nm emission.
Author(s): Hwan-Hee Cho, Univ. of Cambridge (United Kingdom)
10 April 2024 • 16:00 - 16:20 CEST | Berlin/Salon 9, Niveau/Level 0
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Doublet fluorescence from organic radicals has been suggested as a promising route to achieve high efficiency in electroluminescence (EL) with nanosecond decay lifetime, especially for deep red/near-infrared (NIR) emission. Here, a highly efficient and bright doublet emissive system is suggested by combining a thermally activated delayed fluorescence (TADF) host supporting both electron and hole transport and a tris(2,4,6-trichlorophenyl)-methyl-based radical emitter. Strong NIR steady-state photoluminescence (PL) by host photoexcitation demonstrates effective singlet-to-doublet Fӧrster resonance energy transfer. Strong temperature dependence in the delayed emission of transient PL profiles suggests additional energy transfer pathways, in particular triplet-to-doublet Dexter energy transfer. Turning to EL devices, a high maximum external quantum efficiency and radiance of 17.4% and 110,000 mW sr-1 m-2 is achieved with a peak emission wavelength of 707 nm. This new doublet EL design shows the disruptive potential of organic radicals for NIR light-emitting technologies.
Author(s): Alex Farrando-Pérez, Jose M. Villalvilla, Pedro G. Boj, Maria A. Diaz-Garcia, José A. Quintana, Univ. de Alicante (Spain)
10 April 2024 • 16:20 - 16:40 CEST | Berlin/Salon 9, Niveau/Level 0
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Results related to all-solution processed distributed feedback lasers based on a top-layer polymeric resonator geometry will be presented. Such device architecture is very convenient to obtain tunable devices with low threshold and high laser efficiency. Besides, the versatility of the polymeric resonator (a photoresist layer with a surface relief grating, fabricated by holographic lithography and dry etching) has been recently expanded with the demonstration of its use as a stamp to imprint gratings on perovskites. The results presented here include, on the one hand, work related to devices in which the novelty relies on the active compound, which provides improvement on aspects such as the threshold, photostability or the extension of the spectral emission region to the near infrared; and on the other hand, advances on the use of the prepared devices for sensing applications.
Author(s): Jaroslaw Mysliwiec, Wroclaw Univ. of Science and Technology (Poland)
10 April 2024 • 16:40 - 17:00 CEST | Berlin/Salon 9, Niveau/Level 0
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Nowadays, there are many ideas for the realization of distributed feedback (DFB) lasers in either a mono- and bilayer system with a permanent or temporary holographic pattern. Because feedback in DFB lasers can be provided by gain and/or refractive index periodic perturbations, there may be several approaches to their realization, however, dynamic tuning is limited. In our studies we show that using simple systems based on a single organic dye-doped polymeric thin films for distributed feedback, we can get fully reversible spectral tuning of 150 nm. As active compounds we have applied novel push-pull luminescent pyrazoline, diphenylaminofluorene and thiophene derivatives, with different acceptor groups. Integration of such luminescent dyes with transparent polymeric medium allows fabricating real-time lasing tunability in the visible region and first biological window (650-950 nm). Also Excited-State Intramolecular Proton Transfer (ESIPT) compounds, have attracted our considerable attention. Such structure enabled real-time red-green-blue (RGB) switching of emission, both in solution and solid-state, providing white laser light emission.
Author(s): Daan Lenstra, Technische Univ. Eindhoven (Netherlands); Alexis P. Fischer, Lab. de Physique des Lasers, Univ. Sorbonne Paris Nord, CNRS (France); Amani Ouirimi, Nixson Loganathan, Mahmoud Chakaroun, Univ. Sorbonne Paris Nord (France)
10 April 2024 • 17:00 - 17:20 CEST | Berlin/Salon 9, Niveau/Level 0
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We report a theoretical investigation of the recently proposed (Nature 621, 2023, 746) high-speed μ-OLED optically pumped organic laser and confirm that in this configuration the threshold for lasing is much easier reached than in case of a direct-electrically pumped organic laser diode. With a validated model for the electrically pumped OLED, we simulate the generation of pulsed and CW-light. This light is fed into the organic laser where it optically pumps the emitting organic medium The model includes field-enhanced Langevin recombination in the OLED, Stoke-shifted reabsorption in both the OLED and organic laser, with an optical cavity in the latter.
CANCELED: Design, synthesis and application of stable organic luminescent radicals
Author(s): Alim Abdurahman, Jilin Univ. (China)
10 April 2024 • 17:20 - 17:40 CEST | Berlin/Salon 9, Niveau/Level 0
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Stable organic luminescent radicals are a unique class of compounds that possess optical, electrical, and magnetic properties, making them highly promising for a wide range of applications. However, radicals generally exhibit low optical absorption and photoluminescence yields. In this study, we explain the poor optical properties of radicals based on alternant hydrocarbons, and establish design rules to increase the absorption and luminescence yields for donor-acceptor-type radicals. We demonstrate that non-alternant systems are necessary to lift the degeneracy of the lowest energy orbital excitations. Additionally, intensity borrowing from an intense high-lying transition by the low-energy charge-transfer excitation enhances the oscillator strength of the emitter. We apply these rules to design a series of carbon-based luminescent radicals with a high photoluminescence quantum yield (>90%). Organic light-emitting diodes based on these molecules showed a pure-red emission with an external quantum efficiency of over 12%.
10 April 2024 • 17:45 - 19:45 CEST | Galerie Schweitezer, Niveau/Level 0
Conference attendees are invited to attend the Photonics Europe poster session on Wednesday evening. Come view the posters, enjoy light refreshments, ask questions, and network with colleagues in your field. Authors of poster papers will be present to answer questions concerning their papers. Attendees are required to wear their conference registration badges to the poster sessions.

Poster Setup: Wednesday 10:00 - 17:30 hrs
Poster authors, view poster presentation guidelines and set-up instructions at http://spie.org/EPE/poster-presentation-guidelines.
Author(s): Elena Ermilova, Andreas Hertwig, Bundesanstalt für Materialforschung und -prüfung (Germany); Thorsten Döhring, Eva Stanik, Technische Hochschule Aschaffenburg (Germany); Vincenzo Cotroneo, INAF - Osservatorio Astronomico di Brera (Italy); Eugenio Gibertini, Politecnico di Milano (Italy)
On demand | Presented live 10 April 2024
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Although the organic molecule dopamine (3,4-dihydroxyphenethylamine) is commonly known as the “hormone of happiness”, thin films of poly-dopamine also have interesting technical properties. When produced by dip coating, the self-organizing layers grow in a reproducible thickness of single or multiple molecule monolayers of a few nanometer thickness only. In this work, we introduce a method of determining the layer thickness of poly-dopamine on mirrors for astronomical X-ray telescopes. Our method is based on spectroscopic ellipsometry measurements and involves the development of an optical model for the poly-dopamine layers including the dielectric function. Thereby the complex refractive index of the produced layers was determined, covering the range from the ultraviolet to the near infrared spectral region. These measurement results and the corresponding technical challenges are presented in this contribution. Furthermore, an outlook to potential technical applications of this interesting material is given and poly-dopamine layers will make scientist and engineers hopefully happy as an innovative and fascinating technical solution for the future.
Author(s): Siebe Frederix, Melissa Van Landeghem, Sigurd Mertens, Univ. Hasselt (Belgium); Samuele Giannini, David Beljonne, Univ. de Mons (Belgium); Koen Vandewal, Univ. Hasselt (Belgium)
On demand | Presented live 10 April 2024
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In the field organic semiconductor, the sub-bandgap part of the absorption spectrum is often characterized using the empirical Urbach rule. Here, the fitted value of the Urbach energy is used as a measure of the energetic disorder. Despite its widespread adoption, superior methodologies are available for characterizing the absorption tail. Typically, the sub-bandgap region of the absorption spectrum, in an organic donor acceptor blend, comprises three distinct components: absorption arising from localized excitons on the donor/acceptor, absorption originating from the donor acceptor charge transfer (CT) state, and absorption due to midgap trap states. In this work, the excitonic part of the absorption tail is analysed using a Franck-Condon framework, allowing quantification of the static and dynamic excitonic energetic disorder.
Author(s): Binh Minh Nguyen, Markus Schmid, Johann Kirsch, Albin Cakaj, Wolfgang Brütting, Institut für Physik, Univ. Augsburg (Germany)
On demand | Presented live 10 April 2024
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Our work focuses on the potential key factors governing the orientation of emitter molecules in a light-emitting guest-host system within an OLED. Using results from both experimental and simulation studies, we discuss the possible mechanisms that determine the orientation of emitter molecules on the substrate surface, namely the molecular structure, the possibility of forming crystallites, and the ratio between the temperature of the substrate, where the film is grown, and the glass transition temperature of the guest-host system. [1] [1] Nguyen, B. M., Schmid, M., Kirsch, J., Cakaj, A., & Brütting, W. (2023). On the Orientation Mechanism of Nonpolar Dyes in Light-Emitting Guest-Host SystemsChemistry of Materials, 35(17), 7333–7343.
Author(s): Paola Mantegazza, Stefania Moro, Univ. of Birmingham (United Kingdom); Xiaocui Wu, University of Warwick (United Kingdom); Jochen Vanderspikken, Wouter Maes, Institute for Materials Research, Univ. Hasselt (Belgium); Giovanni Costantini, Univ. of Birmingham (United Kingdom)
On demand | Presented live 10 April 2024
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Conjugated polymers (CPs) have attracted significant attention in recent years, due to their exceptional conductive properties and their potential application in organic electronics. The lack of techniques capable of providing structural insights into CPs motivated the Costantini group to explore an alternative characterization approach, based on the combination of electrospray deposition (ESD) with scanning tunneling microscopy (STM). This method allows for a detailed, molecular-scale analysis of the structure and assembly of CPs on surfaces, which is unattainable through the traditional characterisation techniques. This specific study, focuses on the benchmark conjugated polymer pBTTT, investigating the presence of polymerisation defects in two samples synthesized through two different methods. This extensive structural analysis is crucial for establishing a reliable structure-function relationship and advancing environmentally friendly synthetic strategies for these essential functional materials.
Author(s): Nele Theysmans, Univ. Hasselt (Belgium), imec (Belgium); Mathias Fraiponts, Univ. Hasselt (Belgium), Univ. de Namur (Belgium), imec (Belgium); Lisa Reynders, Univ. Hasselt (Belgium); Jasper Deckers, Anitha Ethirajan, Univ. Hasselt (Belgium), imec (Belgium); Benoît Champagne, Univ. de Namur (Belgium); Wouter Maes, Univ. Hasselt (Belgium), imec (Belgium)
On demand | Presented live 10 April 2024
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Traditional cancer treatments have some inherent drawbacks. One of the possible solutions involves the use of an organic photosensitizer (PS) that allows to combine therapy and diagnosis upon simple exposure to light, with minimal side effects. The treatment itself is based on photodynamic therapy. Herein, a PS generates reactive oxygen species (ROS, e.g. singlet oxygen) upon irradiation that will attack the cancer cells. Classical BODIPY dyes are highly fluorescent but unable to realize intersystem crossing to the triplet state, required to generate ROS. Spin-orbit charge-transfer intersystem crossing and the introduction of a twist in the BODIPY scaffold are two separate methods to facilitate intersystem crossing. In our work, these two strategies are combined to realize red-shifted absorption/emission and improved singlet oxygen quantum yields. These results will be discussed in detail in this contribution.
Author(s): Su-Kyung Kim, Tae-Yeon Seong, Korea Univ. (Korea, Republic of)
On demand | Presented live 10 April 2024
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We have developed a new type of transistor that can mimic the functions and behaviors of biological synapses, which are the connections between neurons in the brain. Our transistor has a special polymer layer of cross-linked poly-4-vinyl phenol (PVP), which can form electric-double-layers (EDL) with high capacitance. This layer allows us to control the synaptic weight and the learning ability of our transistor by applying different gate voltages. We also used zinc oxynitride for the channel, which have higher mobility than oxide materials. Unlike conventional memristors, our transistors can perform signal transmission and learning functions simultaneously. It can also emulate a variety of synaptic behaviors such as excitatory postsynaptic current, paired-pulse facilitation, long-term memory, and filtering capability. Our transistor is a promising device for artificial intelligence systems that require brain-like computing.
Author(s): Hung-Yu Pan, Chia-Tse Chang, Chung Yuan Christian Univ. (Taiwan); Russel Cruz Sevilla, Ruth Jeane Soebroto, Hsiu-Ying Huang, Chi-Tsu Yuan, Research Ctr. for Semiconductor Materials and Advanced Optics, Chung Yuan Christian Univ. (Taiwan)
On demand | Presented live 10 April 2024
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Graphene quantum dots (GQDs) are one kind of carbon-based nanomaterials which can be used for numerous applications, such as energy conservation, luminescent solar concentrators, bioimaging, and biosensing. It has low toxicity, high conductivity and it shows exceptional optical properties, including photoluminescence (PL) emission which could be adjusted from blue to red emission depending on the solvent used. Another interesting properties found in GQDs is anti-Stokes photoluminescence (ASPL). However, the mechanism of ASPL in GQDs was still unclear. In this study, GQDs were prepared with 1,3,6-trinitropyrene as the precursor, then dissolved in toluene (GQDs@TL). The results show that GQDs@TL has PL emission peak at ~595 nm when excited at ~530 nm and ~700 nm. It showed that GQDs@TL has large energy gain (~310 meV). To further understand the mechanism of ASPL, additional temperature-dependent measurements were done. We found that the large energy gain could be gained owing to the contribution of phonon energy and hot-band absorption energy (EHBA) coming from molecular and lattice vibration. Therefore, this study will conclude the mechanism of ASPL.
Author(s): Arturs Bundulis, Anete Berzina, Institute of Solid State Physics, Univ. of Latvia (Latvia)
10 April 2024 • 17:45 - 19:45 CEST | Galerie Schweitezer, Niveau/Level 0
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Integrated photonics is an essential topic for novel advances in the communication sector as well as quantum technologies. A special interest has been given to highly nonlinear optical systems that can be used for low-power all-optical processing. Polymer photonics offers a novel approach to all-optical photonics by implementing hybrid-photonic architecture in a single platform - combination of passive polymer host material and active organic dyes as guest material. In this work, we studied the possibility of creating integrated chips for third harmonic generation and frequency comb based on organic dyes that exhibit a strong Kerr effect. In this work we created polymer photonic chips based on polymer – PMMA and SU-8 – that were combined with Kerr organic dye. Chip design was based on waveguide structures in two types of architectures – passive waveguide coated with active dye and waveguide fabrication from a host-guest system consisting of polymer and organic dye.
Author(s): Kwang Ro Yun, Tae-Yeon Seong, Korea Univ. (Korea, Republic of)
On demand | Presented live 10 April 2024
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Utilizing a combination of multi-cation engineering, solvent engineering, and topological engineering, we demonstrated ZnON/FACsPbI3 heterostructures applicable to hybrid phototransistors. To alleviate the defects of ZnON/FACsPbI3 heterointerface, a GuI interface layer was introduced. The influence of the GuI interface layer on the ZnON/FACsPbI3 heterostructure was thoroughly investigated. The ZnON/GuI/FACsPbI3 heterostructure-based hybrid phototransistor demonstrated excellent specific detectability and fast response time.
Author(s): Arwin Goossens, Lize Bynens, Jochen Vanderspikken, Wouter Maes, Koen Vandewal, Univ. Hasselt (Belgium)
On demand | Presented live 10 April 2024
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Organic transistors represent a significant innovation within the realm of flexible and wearable electronics. Organic electrochemical transistors (OECTs) in particular, allow for efficient biosensing applications due to their exceptional sensitivity and transduction capabilities, resulting from the unique electronic and ionic conductivities of the organic materials used. However, challenges include device stability under continuous operation, switching speed, and lack of knowledge on the complex electronic-ionic interactions. In an effort to address these challenges and improve OECT performance, the impact of the removal of homocoupling defects in a series of organic semiconducting polymers, used as the OECT active channel, is studied. Additionally, the effect of this chemical precision on the charge carrier mobility, probed in organic field-effect transistors (OFETs), is investigated.
Author(s): José Gama, CINBIO, Univ. de Vigo (Spain); Marina García-Prado, Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (Spain); Carla Estévez-Varela, Paula Sanmartín-Rodriguéz, CINBIO, Univ. de Vigo (Spain); Pedro Fernandes, INL - International Iberian Nanotechnology Lab. (Portugal); Rosalía Serna, Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (Spain); Isabel Pastoriza-Santos, CINBIO, Univ. de Vigo (Spain); Sara Núñez-Sánchez, Ctr. de Física das Univs. do Minho e do Porto (Portugal)
On demand | Presented live 10 April 2024
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This work presents an innovative library of organic semiconductors that mimic the permittivity properties of metals, enabling the confinement of light at the nanoscale through Surface Exciton Polaritons (SEPs). By self-assembling water-soluble cyanine dyes into J-aggregates, organic semiconductor thin films were fabricated with negative real permittivity values similar to metals. The number of layers in the films was controlled by deposition cycles, resulting in narrow excitonic resonances from visible to infrared wavelengths. The study demonstrated the coupling of light to SEPs at the air/semiconductor interface, offering a new organic semiconductor platform with plasmonic-like properties for applications in energy harvesting and light-propagating devices.
Author(s): Luis Abraham Lozano-Hernández, Isabelle Seguy, Ludovic Salvagnac, Julien Roul, Lab. d'Analyse et d'Architecture des Systèmes, Univ. de Toulouse, CNRS (France); Fabien Lemarchand, Antonin Moreau, Julien Lumeau, Aix-Marseille Univ. (France), Ecole Centrale de Marseille (France), Institut Fresnel, CNRS (France); Veronique Bardinal, Lab. d'Analyse et d'Architecture des Systèmes, Univ. de Toulouse, CNRS (France)
10 April 2024 • 17:45 - 19:45 CEST | Galerie Schweitezer, Niveau/Level 0
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A highly emissive blue organic light emitting diodes (OLED) for use as an algae excitation source in a biosensor was designed and optimized to meet spectral filtering requirements of the system. This source needs to exhibit high emission around 470-480 nm (algae absorption) combined with low emission in the algae fluorescence bandwidth (550-600 nm) in order to avoid any overlapping signal in the biosensor’s sensitivity range. To address these issues, a microcavity device (MOLED) was studied and optimized. In order to further decrease the residual parasitic emission in the green spectral range, an additional filter was also integrated in the device. An improvement in peak intensity of 2.7 times the reference value was obtained, as well as a significant reduction of the parasitic emission in the green range. These improvements in peak intensity and spectral filtering should lead to a suitable blue OLED excitation source for compact optical biosensors.
Author(s): Clint van Hoesel, Reinder Coehoorn, Peter A. Bobbert, Technische Univ. Eindhoven (Netherlands)
10 April 2024 • 17:45 - 19:45 CEST | Galerie Schweitezer, Niveau/Level 0
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It is of utmost importance to understand the effects of exciton-polaron quenching (EPQ) in OLEDs, in order to be able to counteract its detrimental effects. In this work we provide a method for calculating rates of EPQ in phosphorescent emitter-host films based on a combination of theoretical and experimental methods. We model optical spectra and interaction strengths of host molecules carrying a polaron using multi-scale ab initio methods. Emission spectra of the emitter were obtained experimentally, allowing for accurate determination of the Förster EPQ radius (R_(F,EPQ)). Using our method we have determined the Förster radius of the EPQ process for various emitter-host combinations prevalent in phosphorescent OLEDs, as is standard in literature, and compared those results with full interaction calculations. Here we found indications that Dexter-type interactions can play a significant role in TPQ, explaining inconsistencies in simulation-assisted experimental results.
Author(s): Kaishuai Zhang, Univ. Bern (Switzerland)
10 April 2024 • 17:45 - 19:45 CEST | Galerie Schweitezer, Niveau/Level 0
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This study explores the fundamental mechanisms within Organic Electrochemical Transistors (OECTs), focusing on ion transport and electrochemical doping and their effects on electronic charge transport and device stability. By synthesizing novel conjugated polymers with varied side chains and backbones, we aim to optimize the balance between ionic and electronic conductivity, essential for enhancing OECT performance. Employing advanced spectroscopic techniques, including time-resolved and THz spectroscopy, we investigate charge dynamics and the impact of ions on the electronic environment. Additionally, we address device degradation in aqueous environments, crucial for extending OECT longevity. Our findings promise to advance organic electronics by offering insights into high-efficiency, stable OECT design and application.
Hot Topics III
11 April 2024 • 09:00 - 10:35 CEST | Auditorium Schweitzer, Niveau/Level 0
Session Moderator:
Thierry Georges, Oxxius (France)
2024 Symposium Chair

9:00 hrs
Welcome and Opening Remarks
Speaker Introduction
3D laser nanoprinting (Plenary Presentation)
Author(s): Martin Wegener, Karlsruher Institut für Technologie (Germany)
11 April 2024 • 09:05 - 09:50 CEST | Auditorium Schweitzer, Niveau/Level 0
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3D laser nanoprinting based on multi-photon absorption (or multi-step absorption) has become an established commercially available and widespread technology. Here, we focus on recent progress concerning increasing print speed, improving the accessible spatial resolution beyond the diffraction limit, increasing the palette of available materials, and reducing instrument cost.
Author(s): Vasilis Ntziachristos, Helmholtz Zentrum München GmbH (Germany)
11 April 2024 • 09:50 - 10:35 CEST | Auditorium Schweitzer, Niveau/Level 0
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Biological discovery is a driving force of biomedical progress. With rapidly advancing technology to collect and analyze information from cells and tissues, we generate biomedical knowledge at rates never before attainable to science. Nevertheless, conversion of this knowledge to patient benefits remains a slow process. To accelerate the process of reaching solutions for healthcare, it would be important to complement this culture of discovery with a culture of problem-solving in healthcare. The talk focuses on recent progress with optical and optoacoustic technologies, as well as computational methods, which open new paths for solutions in biology and medicine. Particular attention is given on the use of these technologies for early detection and monitoring of disease evolution. The talk further shows new classes of imaging systems and sensors for assessing biochemical and pathophysiological parameters of systemic diseases, complement knowledge from –omic analytics and drive integrated solutions for improving healthcare.
Coffee Break 10:35 - 11:00
Session 8: Organic Photovoltaics II
11 April 2024 • 11:00 - 12:10 CEST | Berlin/Salon 9, Niveau/Level 0
Session Chair: Safa Shoaee, Univ. Potsdam (Germany)
Author(s): Hugo Laval, Lab. d'Intégration du Matériau au Système, Univ. de Bordeaux, CNRS (France); Alexandre Holmes, Institut des Sciences Analytiques et de Physico-Chimie pour l'environment et les Materiaux, Univ. de Pau et des Pays de l'Adour (France); Gwenaël Bonfante, Lab. for Integrated Micro-Mechatronic Systems, CNRS International Research Lab., Institute of Industrial Science, The Univ. of Tokyo (Japan); Guillaume Wantz, Lab. d'Intégration du Matériau au Système, Univ. de Bordeaux, CNRS (France); Anthony Genot, Lab. for Integrated Micro-Mechatronic Systems, CNRS International Research Lab., Institute of Industrial Science, The Univ. of Tokyo (Japan); Christine Lartigau-Dagron, Institut des Sciences Analytiques et de Physico-Chimie pour l'environment et les Materiaux, Univ. de Pau et des Pays de l'Adour (France); Natalie Holmes, The Univ. of Sydney (Australia); Antoine Bousquet, Institut des Sciences Analytiques et de Physico-Chimie pour l'environment et les Materiaux, Univ. de Pau et des Pays de l'Adour (France); Sylvain Chambon, Lab. d'Intégration du Matériau au Système, Univ. de Bordeaux, CNRS (France)
11 April 2024 • 11:00 - 11:30 CEST | Berlin/Salon 9, Niveau/Level 0
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Commonly, the active layers of organic photovoltaic devices (OPV) is deposited from solution-process techniques, using chlorinated and/or aromatic solvents, which have high toxicity for the humans and the environment. In this communication, we intend to present the recent achievements dedicated to development of environmentally-friendly strategy to fabricate (OPV) devices. We have been developing several water-based colloidal inks for eco-friendly process of OPV. By a fine control of the size and the morphology of the nanoparticles, high power conversion efficiencies have been achieved, approaching 10%. This work shows that it is possible to achieve high performances devices from water-based inks by careful control of the nanoparticle and active layer morphology. It opens the route for more environmentally-friendly processes not only for organic photovoltaics but also for organic electronics in general.
Author(s): Xueshi Jiang, Bernhard Siegmund, Koen Vandewal, IMO-IMOMEC, Univ. Hasselt (Belgium)
11 April 2024 • 11:30 - 11:50 CEST | Berlin/Salon 9, Niveau/Level 0
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As a promising candidate to drive low-power, off-grid applications, organic indoor photovoltaics are beginning to attract research attention. In organic photovoltaic devices, charge transport layers are often used to promote the extraction of majority carriers while blocking minority carriers. They can however be a source of device degradation and introduce additional complexity to the fabrication of the device stack. Here, a simplified, yet performant indoor OPV architecture with extended absorber thickness, but without electron transport layer (ETL) is demonstrated. We show that the diminished impact of the ETL on indoor OPV results from a drastically reduced surface recombination in thick absorber devices. The proposed simplified device architecture with thick absorber has great potential in large-scale production.
Author(s): Bowen Sun, Univ. Potsdam (Germany)
11 April 2024 • 11:50 - 12:10 CEST | Berlin/Salon 9, Niveau/Level 0
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While efficient charge generation despite ultra-low energy offsets (down to 0 eV offsets) between donor and acceptor in non-fullerene acceptor (NFA) based organic solar cells has been often reported, the physical meaning of this observation is discussable and unclear. In our work, in terms of a series of donor:NFA combinations, and by combining advanced experimental techniques and optical and electrical simualtions, the role of energetic offset and the pathways for carrier losses has been studied in detail.
Lunch Break 12:10 - 13:30
Session 9: New Materials, Concepts, and Devices I
11 April 2024 • 13:30 - 15:00 CEST | Berlin/Salon 9, Niveau/Level 0
Session Chair: Shuzo Hirata, The Univ. of Electro-Communications (Japan)
Author(s): Natalie Stingelin, Georgia Institute of Technology (United States)
11 April 2024 • 13:30 - 14:00 CEST | Berlin/Salon 9, Niveau/Level 0
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We present here novel optical materials based on oxide hydrate/poly(vinyl alcohol) hybrids that have a readily tunable refractive index and can be solution-processed into photonic structures, including dielectric mirrors, gratings, and beyond. Specific focus will be given on the demonstration of the use of these materials for the realization of planar microcavities. Reassuringly, strong light–matter coupling is achieved at the target excitation. Indeed, the energy-dispersion relation in reflectance and the group delay of transmitted light in the microcavities show a clear anti-crossing—an energy gap between two distinct exciton-polariton dispersion branches. The agreement between classical electrodynamic simulations of the microcavity response and the experimental data demonstrates that the entire microcavity stack can be controllably produced as designed. Because of the versatility of the hybrid material used in these microcavities as high refractive index material, structures with a wide spectral range of optical modes might be designed and produced with straightforward coating methodologies, enabling fine-tuning of the energy and lifetime of the microcavities‘ optical modes to h
Author(s): Ivan V. Komissarov, Brendan Habert, Univ. of Rochester (United States); Lizaveta A. Dronina, Alexandr L. Danilyuk, Belarusian State Univ. of Informatics and Radioelectronics (Belarus); Matteo Salvato, Univ. degli Studi di Roma "Tor Vergata" (Italy); Serghej L. Prischepa, Belarusian State Univ. of Informatics and Radioelectronics (Belarus); Roman Sobolewski, Univ. of Rochester (United States)
11 April 2024 • 14:00 - 14:20 CEST | Berlin/Salon 9, Niveau/Level 0
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We performed comprehensive studies of current transport across SWCNT-Si heterojunctions, considered as a promising component for advanced photodetectors. Low-doped n-type Si was used as a substrate and SWCNT films were deposited on its top by a wet method out of solutions. We collected current-voltage (I-V) characteristics of the heterojunctions in the 78-300 K temperature range under dark conditions. In the forward bias, the I-V curves exhibited two regimes, namely, the “low” and “high” voltage regimes. We applied the Cheung–Cheung method to evaluate the height of the Schottky barrier, the series resistance, and the ideality factor, for both regimes. For tested samples, the ideality factor is very well fitted with the T-1/2 dependence. The slope of this dependency for the “high” voltage regime decreases with the increase of the SWCNT concentration, what agrees with the Card–Rhoderick model that the slope in this regime should be inversely proportional to the density of states at the SWCNT/SiO2 interface, which in turn is proportional to the SWCNT concentration. The crossover voltage between the two voltage regimes decreased linearly with the temperature for all our samples.
Author(s): Arne Meulemans, Daniel Escudero, KU Leuven (Belgium)
11 April 2024 • 14:20 - 14:40 CEST | Berlin/Salon 9, Niveau/Level 0
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Organic Thermoelectric materials (OTE) show potential as a material for the production of green energy, through conversion of heat to electricity. Among OTE materials, polythiophenes are excellent candidates, although their structure-property relationships are to date poorly understood. Figuring out the structure-property relationships are particularly challenging for organic semiconducting polymers because of their often complex semicrystalline structures and the big level of uncertainty regarding the detailed structure and composition of the polymers. In this study we present a modelling study of the morphological properties of polythiophenes. We present a computational protocol, using molecular dynamics (MD) with GAFF2 forcefields, able to generate the complex semicrystalline structures of these polymers and explain how different simulation parameters/conditions impact the results.
Author(s): Margherita Bolognesi, Emilia Benvenuti, Marco Natali, Salvatore Moschetto, Mario Prosa, Stefano Toffanin, Istituto per lo Studio dei Materiali Nanostrutturati, Consiglio Nazionale delle Ricerche (Italy); Marco Angelini, Optics For Life (Italy); Franco Marabelli, Univ. degli Studi di Pavia (Italy); Paola Pellacani, Plasmore S.r.l. (Italy)
11 April 2024 • 14:40 - 15:00 CEST | Berlin/Salon 9, Niveau/Level 0
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On-site analysis of multiple analytes from different classes (such as heavy metals, proteins and small molecules), at the sensitivity required for a selected application, is a hard technological challenge. In this context, optical sensing in miniaturized systems has the largest potential. Baser on our previous findings,[1-3] we present here the design and optimization of a miniaturized optical sensor with multiple channels, capable of multimodal optical detection in each channel, and the proof-of-concept realization of sub-systems providing two complementary detection modes: plasmon enhanced fluorescence and localized surface plasmon resonance. The multichannel (enabling multiplexing) and multimodal optical sensor is designed to have a total size of one inch-square and optimized sensing performance, obtained by combining organic optoelectronic and nanoplasmonic components. [12] M. Prosa et al., Adv. Funct. Mater. 31 (2021). [13] M. Bolognesi et al., Adv. Mater. 2208719 (2023) 1–13. [14] F. Floris et al., Mater. Proc. 14 (2023) 1–5.
Coffee Break 15:00 - 15:30
Session 10: New Materials, Concepts, and Devices II
11 April 2024 • 15:30 - 16:30 CEST | Berlin/Salon 9, Niveau/Level 0
Session Chair: Sebastian Schellhammer, TU Dresden (Germany)
Author(s): Jesse A. Wisch, Kelvin A. Green, Amélie C. Lemay, Yiling Q. Li, Tersoo Upaa, Barry P. Rand, Princeton Univ. (United States)
11 April 2024 • 15:30 - 15:50 CEST | Berlin/Salon 9, Niveau/Level 0
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While solid-state upconversion systems promise applications in solar cells, photoredox catalysis, and bioimaging; most require tremendous optical power to achieve maximum upconversion efficiency. In this work, we lower this required optical power by using the concentrated electric field of surface plasmons generated from an organic light emitting diode. Excitons formed within the diode launch surface plasmons into a metallic cathode. On the opposite side of this cathode, those surface plasmons excite the triplet sensitizer of an upconversion film with a skin depth of only tens of nanometers. We find that the power required to reach half of the maximum upconversion efficiency is lowered by over one order of magnitude compared to conventional laser excitation and is crossed at a diode current density of only 1 mA/cm2. These mild conditions may allow for more practical applications of solid-state upconversion systems.
Author(s): Bram Bijnens, Sam Gielen, Wouter Maes, Koen Vandewal, Univ. Hasselt (Belgium)
11 April 2024 • 15:50 - 16:10 CEST | Berlin/Salon 9, Niveau/Level 0
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The current state-of-the-art infrared (IR) systems use inorganic semiconductors for so-called photonic detection in the near (few μm) and mid-IR (10’s of μm) range and switch to thermal detection systems such as bolometers for the large wavelength regimes (up to mm range). In order to lower the cost of IR detectors, much effort is put into designing low-gap polymers or molecules for organic photo-detectors, but their detection range is currently still limited to 1500-1600 nm wavelengths, with modest detectivities in comparison to existing inorganic technologies in the short wave infrared (SWIR) range. In this work, we look at the possibility of using organic semiconductors in a bolometric device for infrared detection over an extensive wavelength range, spanning from the SWIR to the mid-IR. We find advantages of using organic materials compared to inorganic materials for the fabrication of bolometers and use theoretical modeling to guide us on which parameters we can use to optimize our devices. We find two key parameters determining the device performance: the polymers’ thermal conductivity and the overall device thickness.
Author(s): Patricija Paulsone, Ilze Aulika, Jelena Butikova, Adriana Maurucaite, Kitija Alise Štucere, Aivars Vembris, Institute of Solid State Physics, Univ. of Latvia (Latvia)
11 April 2024 • 16:10 - 16:30 CEST | Berlin/Salon 9, Niveau/Level 0
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In this work, single layer 3,3′-Di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP), tris(4-carbazoyl-9-ylphenyl)amine (TCTA) and 4,6-Bis(3,5-di-3-pyridinylphenyl)-2-methylpyrimidine (B3PymPm) organic thin films optical properties were investigated by spectroscopic ellipsometry and spectrophotometer. Films were fabricated by thermal evaporation on glass, quartz, and indium tin oxide (ITO) substrates. The substrate impact on complex refractive index and absorption coefficient of thin films is evaluated and discussed.
Conference Chair
TU Dresden (Germany)
Conference Chair
Univ. Hasselt (Belgium)
Conference Chair
Univ. Hasselt (Belgium)
Program Committee
Univ. Bern (Switzerland)
Program Committee
Univ. de Mons (Belgium)
Program Committee
Univ. of St. Andrews (United Kingdom)
Program Committee
Georgia Institute of Technology (United States)
Program Committee
Univ. of St. Andrews (United Kingdom)
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