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Untangling Photofaradaic and Photocapacitive Effects in Organic Optoelectronic Stimulation Devices
摘要： Light, as a versatile and non-invasive means to elicit a physiological response, offers solutions to problems in basic research as well as in biomedical technologies. The complexity and limitations of optogenetic methods motivate research and development of optoelectronic alternatives. A recently growing subset of approaches relies on organic semiconductors as the active light absorber. Organic semiconductors stand out due to their high optical absorbance coefficients, mechanical flexibility, ability to operate in a wet environment, and potential biocompatibility. They could enable ultrathin and minimally invasive form factors not accessible with traditional inorganic materials. Organic semiconductors, upon photoexcitation in an aqueous medium, can transduce light into (1) photothermal heating, (2) photochemical/photocatalytic redox reactions, (3) photocapacitive charging of electrolytic double layers, and (4) photofaradaic reactions. In realistic conditions, different effects may coexist, and understanding their role in observed physiological phenomena is an area of critical interest. This article serves to evaluate the emerging picture of photofaradaic vs. photocapacitive effects in the context of our group’s research efforts and that of others over the past few years. We present simple experiments which can be used to benchmark organic optoelectronic stimulation devices.
关键词： neurostimulation,photostimulation,bioelectronics,organic electronics,photoelectrochemistry
更新于2025-09-23 15:21:01
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Synthesis and Evaluation of Scalable D-A-D ??-Extended Oligomers as p-Type Organic Materials for Bulk-Heterojunction Solar Cells
摘要： The synthesis and characterization of four novel donor-acceptor-donor π-extended oligomers, incorporating naphtha(1–b)thiophene-4-carboxylate or benzo(b)thieno(3,2-g) benzothiophene-4-carboxylate 2-octyldodecyl esters as end-capping moieties, and two different conjugated core fragments, is reported. The end-capping moieties are obtained via a cascade sequence of sustainable organic reactions, and then coupled to benzo(c)(1,2,5)thiadiazole and its difluoro derivative as the electron-poor π-conjugated cores. The optoelectronic properties of the oligomers are reported. The novel compounds revealed good film forming properties, and when tested in bulk-heterojunction organic photovoltaic cell devices in combination with PC61BM, revealed good fill factors, but low efficiencies, due to their poor absorption profiles.
关键词： organic electronics,Cascade organic reactions,fused aromatic rings,organic photovoltaics,π-conjugated oligomers,bulk-heterojunction organic solar cells,direct arylation
更新于2025-09-23 15:19:57
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Chargea??Transfera??Controlled Growth of Organic Semiconductor Crystals on Graphene
摘要： Controlling the growth behavior of organic semiconductors (OSCs) is essential because it determines their optoelectronic properties. In order to accomplish this, graphene templates with electronic-state tunability are used to affect the growth of OSCs by controlling the van der Waals interaction between OSC ad-molecules and graphene. However, in many graphene-molecule systems, the charge transfer between an ad-molecule and a graphene template causes another important interaction. This charge-transfer-induced interaction is never considered in the growth scheme of OSCs. Here, the effects of charge transfer on the formation of graphene–OSC heterostructures are investigated, using fullerene (C60) as a model compound. By in situ electrical doping of a graphene template to suppress the charge transfer between C60 ad-molecules and graphene, the layer-by-layer growth of a C60 film on graphene can be achieved. Under this condition, the graphene–C60 interface is free of Fermi-level pinning; thus, barristors fabricated on the graphene–C60 interface show a nearly ideal Schottky–Mott limit with efficient modulation of the charge-injection barrier. Moreover, the optimized C60 film exhibits a high field-effect electron mobility of 2.5 cm2 V?1 s?1. These results provide an efficient route to engineering highly efficient optoelectronic graphene–OSC hybrid material applications.
关键词： growth template,organic semiconductors,organic electronics,graphene,charge transfer
更新于2025-09-23 15:19:57
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High Performance Organic Solar Cells Fabricated Using Recycled Transparent Conductive Substrates
摘要： The power conversion e?ciency (PCE) of organic solar cells (OSCs) has been gradually increasing over the past years, but these emerging photovoltaic devices still su?er from relatively short lifetimes. To promote circular economy and reduce costly electronic materials wastes, we explore the possibility of recycling durable zinc oxide coated indium tin oxide (ITO/ZnO) from nonfullerene OSCs through sequential ultrasonication in a series of solvents followed by thermal annealing. With the adequate cleaning sequence, the recycled ITO/ZnO substrates produce PCEs of 8.65%, a value comparable to the PCEs obtained with freshly prepared substrates (8.73%). Our results also indicate that isopropanol gradually removes the zinc oxide layer and should thus be avoided when attempting multiple successive recycling of the same substrate. ITO/ZnO substrates recycled 10 times with and without isopropanol yield PCEs of 5.14% and 7.93%, respectively. By optimizing the recycling procedure, we introduce a simple strategy to considerably increase the lifecycle of transparent electrode substrates employed in organic electronic devices and decrease the amount of wastes from the electronic industry.
关键词： Recycling,Zinc oxide,PBDB-T,Organic electronics,Nonfullerene acceptors
更新于2025-09-23 15:19:57
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Lighta??Emitting Electrochemical Cells Based on Colora??Tunable Inorganic Colloidal Quantum Dots
摘要： Large-area, ultrathin light-emitting devices currently inspire architects and interior and automotive designers all over the world. Light-emitting electrochemical cells (LECs) and quantum dot light-emitting diodes (QD-LEDs) belong to the most promising next-generation device concepts for future flexible and large-area lighting technologies. Both concepts incorporate solution-based fabrication techniques, which makes them attractive for low cost applications based on, for example, roll-to-roll fabrication or inkjet printing. However, both concepts have unique benefits that justify their appeal. LECs comprise ionic species in the active layer, which leads to the omission of additional organic charge injection and transport layers and reactive cathode materials, thus LECs impress with their simple device architecture. QD-LEDs impress with purity and opulence of available colors: colloidal quantum dots (QDs) are semiconducting nanocrystals that show high yield light emission, which can be easily tuned over the whole visible spectrum by material composition and size. Emerging technologies that unite the potential of both concepts (LEC and QD-LED) are covered, either by extending a typical LEC architecture with additional QDs, or by replacing the entire organic LEC emitter with QDs or perovskite nanocrystals, still keeping the easy LEC setup featured by the incorporation of mobile ions.
关键词： organic electronics,perovskites,luminescence,light-emitting electrochemical cells,quantum dots
更新于2025-09-23 15:19:57
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Comparison of spin-on-glass and WO <sub/>3</sub> as an insulating layer for printed resistive memory devices
摘要： Resistive Random Access Memory (ReRAM) is a highly promising technology for various future memory applications. In this work, spin-on-glass (SOG) and WO3 nanoparticles are used as an insulating layer for completely inkjet-printed ReRAM cells. The direct comparison shows that the di?erence in switching parameters can be used to serve di?erent device requirements for various applications. While local ?lament formation with conductive atomic force microscopy con?rms the same switching mechanism for both compounds, the current–voltage characteristics di?er from each other. SOG as excellent insulator shows an OFF resistance in the range of GΩ and is therefore highly suitable for multi-bit data storage to increase memory density. ReRAM cells with WO3 face larger leakage currents and show a low degree of multi-bit data storage. However, WO3 can be used to fabricate completely sinter-free memory devices for applications which do not allow high temperatures in the fabrication process.
关键词： spin-on-glass,?exible electronics,printed electronics,organic electronics,inkjet printing,ReRAM
更新于2025-09-19 17:15:36
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The electronic applications of stable diradicaloids: present and future
摘要： Organic molecules with unpaired electrons are intriguing for advanced applications in molecular electronics, spintronics and organic batteries, as well as other possible applications. Among them, diradicaloids have received growing attention due to the characteristic resonance structures between open-shell and closed-shell forms that lead to unique properties such as low energy bandgap and strong intermolecular spin–spin interaction. Therefore, in recent years, vast efforts have been devoted to investigate the synthesis, structure and fundamental properties of diradicaloids. However, the electronic applications of diradicaloids still remain in an early stage. Only a few diradicaloids have already found their place in electronic devices. In this perspective, we summarize the recent development of electronic applications of stable diradicaloids. The challenges and opportunities of stable diradicaloids for future electronic applications are also discussed.
关键词： spintronics,organic electronics,organic batteries,OFETs,NIR dyes,OPDs,diradicaloids,electronic applications
更新于2025-09-19 17:15:36
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Naphthalene and perylene diimides – better alternatives to fullerenes for organic electronics?
摘要： The LUMO levels of rylene diimides are highly comparable to those of fullerenes but this class of molecules offers tunability of both HOMO and LUMO levels and the related band gap by either simple substitution at the aromatic core or annulation to give expanded p-scaffolds. In this article we highlight the most outstanding achievements during the last decade in terms of charge carrier mobility for organic thin-film and single crystal field-effect transistors as well as photovoltaic performance for both small molecule and polymeric compounds.
关键词： fullerenes,perylene diimides,organic electronics,photovoltaic performance,naphthalene diimides,charge carrier mobility
更新于2025-09-19 17:15:36
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Ultra-Thick Organic Pigment Layer Up to 10 ??m Activated by Crystallization in Organic Photovoltaic Cells
摘要： Organic optoelectronic devices tend to have limited thickness. Organic light emitting diodes (OLED) and organic photovoltaic cells (OPV) made of organic pigments are typically with thickness of a few or a few tens of nanometers. Thickness of organic photovoltaic cells made with polymers exceeds them typically up to the order of a few 100 nm but still necessarily co-optimized with respect to light absorption and charge transport. Here, we demonstrate that crystallization made a 10-μm-thick pigment layer active in a photovoltaic cell, using a prototypical pair of pigments, phthalocyanine, and fullerene. It is proved that crystalline pigment layer with a thickness much greater than what is needed for optical optimization can be utilized for organic optoelectronic devices and that organic optoelectronic devices have potentiality to relief their design from co-optimization of optics and charge transport.
关键词： bulk hetero-junction,organic electronics,crystallization,organic photovoltaics,pigment,solar cell
更新于2025-09-19 17:13:59
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Fluorinated dithienyl-diketopyrrolopyrrole: a new building block for organic optoelectronic materials
摘要： Diketopyrrolopyrrole (DPP) derivatives have been widely used as the electron-withdrawing unit to construct donor–acceptor (D–A) conjugated systems in organic electronics. The 3,6-position flanking aromatic rings of DPP could strongly influence the optoelectronic properties of DPP-based materials. In this study, a stepwise synthesis strategy was used to prepare monofluorinated and difluorinated dithienyl-DPP. The single crystal of the difluorinated model compound was also obtained. Three polymers based on bithiophene donor and dithienyl-DPP acceptor with different fluorinated positions were synthesized. And preliminary investigations of the influence of fluorination on the optoelectronic properties were performed.
关键词： dithienyl-DPP,Diketopyrrolopyrrole,optoelectronic properties,organic electronics,fluorinated
更新于2025-09-16 10:30:52