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Asymmetric Electron Acceptors for Higha??Efficiency and Lowa??Energya??Loss Organic Photovoltaics
摘要： Low energy loss and efficient charge separation under small driving forces are the prerequisites for realizing high power conversion efficiency (PCE) in organic photovoltaics (OPVs). Here, a new molecular design of nonfullerene acceptors (NFAs) is proposed to address above two issues simultaneously by introducing asymmetric terminals. Two NFAs, BTP-S1 and BTP-S2, are constructed by introducing halogenated indandione (A1) and 3-dicyanomethylene-1-indanone (A2) as two different conjugated terminals on the central fused core (D), wherein they share the same backbone as well-known NFA Y6, but at different terminals. Such asymmetric NFAs with A1-D-A2 structure exhibit superior photovoltaic properties when blended with polymer donor PM6. Energy loss analysis reveals that asymmetric molecule BTP-S2 with six chlorine atoms attached at the terminals enables the corresponding devices to give an outstanding electroluminescence quantum efficiency of 2.3 × 10?2%, one order of magnitude higher than devices based on symmetric Y6 (4.4 × 10?3%), thus significantly lowering the nonradiative loss and energy loss of the corresponding devices. Besides, asymmetric BTP-S1 and BTP-S2 with multiple halogen atoms at the terminals exhibit fast hole transfer to the donor PM6. As a result, OPVs based on the PM6:BTP-S2 blend realize a PCE of 16.37%, higher than that (15.79%) of PM6:Y6-based OPVs. A further optimization of the ternary blend (PM6:Y6:BTP-S2) results in a best PCE of 17.43%, which is among the highest efficiencies for single-junction OPVs. This work provides an effective approach to simultaneously lower the energy loss and promote the charge separation of OPVs by molecular design strategy.
关键词： asymmetric acceptors,molecular design strategies,nonfullerene acceptors,charge separation,organic photovoltaics
更新于2025-09-23 15:21:01
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Towards photovoltaic windows: scalable fabrication of semitransparent modules based on non-fullerene acceptors <i>via</i> laser-patterning
摘要： Semitransparent organic photovoltaics (OPV) possess unique properties that make them highly appealing for their integration into semitransparent architectonic elements such as windows or glazings. In order to provide sufficient transparency, non-opaque electrodes and thin photoactive layers are typically used, thus limiting the light-harvesting capacity. This can be partially overcome by using materials that absorb light mostly in the infrared region. On the other hand, the use of scalable techniques for the fabrication of semitransparent devices is often disregarded. In this work, we combine the blue, low-bandgap polymer PBTZT-stat-BDTT-8 with the near-infrared absorbing non-fullerene acceptor 4TICO, adapting the module fabrication to low-cost manufacturing processes that are compatible with large-scale production. Fully solution-processed semitransparent solar cells over 4.7% performance are prepared from non-chlorinated formulations, in air and using scalable techniques such as blade coating. Our prototypes of semitransparent laser-patterned OPV modules exceed 30% of transparency (measured as human perception transmittance, HPT) and yield efficiencies in the range of 4%, geometrical fill factors surpassing 90% and an active area above 1 cm2. We verify the quality of cell-to-cell interconnection and optimise the geometry of the modules with the help of local optoelectronic imaging techniques. This work highlights the relevance of non-fullerene acceptors with strong absorption in the near-infrared, as they can meet industrial and technical requirements for the upscaling and integration of high-performance semitransparent OPV modules with low production costs.
关键词： scalable fabrication,laser-patterning,non-fullerene acceptors,photovoltaic windows,semitransparent organic photovoltaics
更新于2025-09-23 15:21:01
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Higha??Performance Tandem Organic Solar Cells Using HSolar as the Interconnecting Layer
摘要： Tandem structure provides a practical way to realize high efficiency organic photovoltaic cells, it can be used to extend the wavelength coverage for light harvesting. The interconnecting layer (ICL) between sub-cells plays a critical role in the reproducibility and performance of tandem solar cells, yet the processability of the ICL has been a challenge. In this work the fabrication of highly reproducible and efficient tandem solar cells by employing a commercially available material, PEDOT:PSS HTL Solar (HSolar), as the hole transporting material used for the ICL is reported. Comparing with the conventional PEDOT:PSS Al 4083 (c-PEDOT), HSolar offers a better wettability on the underlying nonfullerene photoactive layers, resulting in better charge extraction properties of the ICL. When FTAZ:IT-M and PTB7-Th:IEICO-4F are used as the subcells, a power conversion efficiency (PCE) of 14.7% is achieved in the tandem solar cell. To validate the processability of these tandem solar cells, three other research groups have successfully fabricated tandem devices using the same recipe and the highest PCE obtained is 16.1%. With further development of donor polymers and device optimization, the device simulation results show that a PCE > 22% can be realized in tandem cells in the near future.
关键词： interconnecting layers,tandem solar cells,organic photovoltaics
更新于2025-09-23 15:21:01
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4H-pyranylidene-based small push-pull chromophores: Synthesis, structure, electronic properties and photovoltaic evaluation
摘要： The synthesis and electrochemical and optical characterizations of four new 4H-pyranylidene-based push-pull molecules are reported herein as well as their evaluation as donor materials for organic photovoltaics. Studied systems exhibit good absorption properties and appropriate LUMO levels for a photoinduced electron transfer to C60. Bilayer organic solar cells fabricated from these new donors and C60 as the acceptor gave photocurrent however with low power conversion efficiencies. As shown by X-ray diffraction and theoretical calculations, titled molecules present a twisted structure which may prevent the formation of suitable π-π contacts between adjacent molecules hence explaining their low photovoltaic performance.
关键词： Push-pull systems,Small conjugated molecules,4H-pyranylidene,Organic photovoltaics
更新于2025-09-23 15:21:01
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Tackling Performance Challenges in Organic Photovoltaics: An Overview about Compatibilizers
摘要： Organic Photovoltaics (OPVs) based on Bulk Heterojunction (BHJ) blends are a mature technology. Having started their intensive development two decades ago, their low cost, processability and flexibility rapidly funneled the interest of the scientific community, searching for new solutions to expand solar photovoltaics market and promote sustainable development. However, their robust implementation is hampered by some issues, concerning the choice of the donor/acceptor materials, the device thermal/photo-stability, and, last but not least, their morphology. Indeed, the morphological profile of BHJs has a strong impact over charge generation, collection, and recombination processes; control over nano/microstructural morphology would be desirable, aiming at finely tuning the device performance and overcoming those previously mentioned critical issues. The employ of compatibilizers has emerged as a promising, economically sustainable, and widely applicable approach for the donor/acceptor interface (D/A-I) optimization. Thus, improvements in the global performance of the devices can be achieved without making use of more complex architectures. Even though several materials have been deeply documented and reported as effective compatibilizing agents, scientific reports are quite fragmentary. Here we would like to offer a panoramic overview of the literature on compatibilizers, focusing on the progression documented in the last decade.
关键词： mixing interfaces,additives,bulk heterojunction,morphology modulators,donor/acceptor interface,organic photovoltaics,compatibilizers
更新于2025-09-23 15:21:01
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Narrowing the Band Gap: The Key to High-Performance Organic Photovoltaics
摘要： Organic photovoltaics (OPVs) have attracted considerable attention in the last two decades to overcome the terawatt energy challenge and serious environmental problems. During their early development, only wide-band-gap organic semiconductors were synthesized and employed as the active layer, mainly utilizing photons in the UV?visible region and yielding power conversion e?ciencies (PCEs) lower than 5%. Afterward, considerable e?orts were made to narrow the polymer donor band gap in order to utilize the infrared photons, which led to the enhancement of the PCE from 5% to 12% in about a decade. Since 2017, the study of narrow-band-gap non-fullerene acceptors helped usher in a new era in OPV research and boosted the achievable the PCE to 17% in only 3 years. In essence, the history of OPV development in the last 15 years can be summarized as an attempt to narrow the band gap of organic semiconductors and better position the energy levels. There are multiple bene?ts of a narrower band gap: (1) considerable infrared photons can be utilized, and as a result, the short-circuit current density can increase signi?cantly; (2) the energy o?set of the lowest unoccupied molecular orbital energy levels or highest occupied molecular orbital energy levels between the donor and acceptor can be reduced, which will reduce the open-circuit voltage loss by minimizing the loss caused by the donor/acceptor charge transfer state; (3) because of the unique molecular orbitals of organic semiconductors, the red-shifted absorption will induce high transmittance in the visible region, which is ideal for the rear subcells in tandem-junction OPVs and transparent OPVs.
关键词： Organic photovoltaics,narrow-band-gap,non-fullerene acceptors,power conversion efficiencies,polymer donors
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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A photovoltaic textile design with a stainless steel mesh fabric
摘要： Solar energy is one of the most popular energy sources among the other renewable energies. Photovoltaic technology is a clean way to generate electricity from sunlight. Flexible photovoltaics enable portable electronic devices to power at off-grid conditions. Stainless steel mesh fabric was used as a substrate and electrode allowing the light to reach the photoactive layer. The photoactive layer and hole transport layer were deposited by the means of dip-coating like in the textile industry. The metal back electrode was evaporated in a thermal evaporator under vacuum. Promising results were obtained from photovoltaic measurements. About 0.69% power conversion efficiency was obtained from textile-based solar cells in this study. The textile-based metal fabric enables a flexible photovoltaic structure that can be integrated on non-planar surfaces to generate electricity, and also mesh structure allows the light to reach the photoactive layer.
关键词： solar textiles,conductive fabric,flexible photovoltaics,organic photovoltaics,Wearable electronics
更新于2025-09-23 15:19:57
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Rational design of pyrrolopyrrole-aza-BODIPY-based acceptora??donora??acceptor triads for organic photovoltaics application
摘要： Acceptor-donor-acceptor triads consisting of diketopyrrolopyrrole (DPP) or pyrrolopyrrole aza-BODIPY (PPAB) or both as acceptors and cyclopentadithiophene as a donor were rationally designed for near infrared (NIR) photovoltaics application. Among them, the PPAB-based triad exhibited the highest power conversion efficiency of 3.88% owing to the panchromatic absorption in the UV/vis/NIR regions.
关键词： pyrrolopyrrole-aza-BODIPY,organic photovoltaics,acceptor-donor-acceptor triads,near infrared photovoltaics
更新于2025-09-23 15:19:57
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In situ Measuring Film-Depth-Dependent Light Absorption Spectra for Organic Photovoltaics
摘要： Organic donor–acceptor bulk heterojunction are attracting wide interests for solar cell applications due to solution processability, mechanical ?exibility, and low cost. The photovoltaic performance of such thin ?lm is strongly dependent on vertical phase separation of each component. Although ?lm-depth-dependent light absorption spectra measured by non-in situ methods have been used to investigate the ?lm-depth pro?ling of organic semiconducting thin ?lms, the in situ measurement is still not well-resolved. In this work, we propose an in situ measurement method in combination with a self-developed in situ instrument, which integrates a capacitive coupled plasma generator, a light source, and a spectrometer. This in situ method and instrument are easily accessible and easily equipped in laboratories of the organic electronics, which could be used to conveniently investigate the ?lm-depth-dependent optical and electronic properties.
关键词： light absorption,bulk heterojunction,spectroscopy,organic solar cells,depth pro?ling,organic photovoltaics
更新于2025-09-23 15:19:57