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Thermally Durable Nonfullerene Acceptor with Nonplanar Conjugated Backbone for Higha??Performance Organic Solar Cells
摘要： A nonfullerene acceptor (NFA) with acceptor–donor–acceptor (A–D–A) architecture, i-IEICO-2F, based on 4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene as an electron-donating core and 2-(6-fluoro-2,3-dihydro-3-oxo-1H-inden-1-ylidene)-propanedinitrile as electron-withdrawing end groups, is designed and synthesized. i-IEICO-2F has a twist structure in the main conjugated chain, which causes blueshifted absorption and leads to harmonious absorption with a high bandgap donor. The bandgap of i-IEICO-2F compliments the bandgap of suitable wide bandgap donor polymers such as J52, leading to complete light absorption throughout the visible spectrum. Devices based on i-IEICO-2F exhibit optimized photovoltaic performance including an open-circuit voltage of 0.93 V, a short-circuit current density of 16.61 mA cm?2, and a fill factor of 73%, and result in a power conversion efficiency (PCE) of 11.28%. The i-IEICO-2F-based devices reach PCEs of >11% without using any additives or post-treatments. Devices are found to be thermally stable and maintain 44% of their initial PCE after 184.5 h of continuous thermal annealing (TA) treatment at 150 °C. Based on UV, atomic force microscopy (AFM), and grazing incidence wide angle X-ray scattering (GIWAXS) results, i-IEICO-2F devices show almost identical morphology and molecular orientation throughout the TA treatment and excellent stability compared to other IEICO derivatives.
关键词： twist structure,solar cells,nonfullerene acceptors,synthesis,fluorine
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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Efficient Organic Solar Cell with 16.88% Efficiency Enabled by Refined Acceptor Crystallization and Morphology with Improved Charge Transfer and Transport Properties
摘要： Single-layered organic solar cells (OSCs) using nonfullerene acceptors have reached 16% efficiency. Such a breakthrough has inspired new sparks for the development of the next generation of OSC materials. In addition to the optimization of electronic structure, it is important to investigate the essential solid-state structure that guides the high efficiency of bulk heterojunction blends, which provides insight in understanding how to pair an efficient donor–acceptor mixture and refine film morphology. In this study, a thorough analysis is executed to reveal morphology details, and the results demonstrate that Y6 can form a unique 2D packing with a polymer-like conjugated backbone oriented normal to the substrate, controlled by the processing solvent and thermal annealing conditions. Such morphology provides improved carrier transport and ultrafast hole and electron transfer, leading to improved device performance, and the best optimized device shows a power conversion efficiency of 16.88% (16.4% certified). This work reveals the importance of film morphology and the mechanism by which it affects device performance. A full set of analytical methods and processing conditions are executed to achieve high efficiency solar cells from materials design to device optimization, which will be useful in future OSC technology development.
关键词： multilength-scaled morphology,nonfullerene acceptors,power conversion efficiency,organic solar cells,2D electron transport
更新于2025-09-23 15:19:57
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Reducing the Singleta??Triplet Energy Gap by Enda??Group ??a???? Stacking Toward Higha??Efficiency Organic Photovoltaics
摘要： To improve the power conversion efficiencies for organic solar cells, it is necessary to enhance light absorption and reduce energy loss simultaneously. Both the lowest singlet (S1) and triplet (T1) excited states need to energetically approach the charge-transfer state to reduce the energy loss in exciton dissociation and by triplet recombination. Meanwhile, the S1 energy needs to be decreased to broaden light absorption. Therefore, it is imperative to reduce the singlet?triplet energy gap (ΔEST), particularly for the narrow-bandgap materials that determine the device T1 energy. Although maximizing intramolecular push?pull effect can drastically decrease ΔEST, it inevitably results in weak oscillator strength and light absorption. Herein, large oscillator strength (≈3) and a moderate ΔEST (0.4?0.5 eV) are found for state-of-the-art A?D?A small-molecule acceptors (ITIC, IT-4F, and Y6) owing to modest push?pull effect. Importantly, end-group π?π stacking commonly in the films can substantially decrease the S1 energy by nearly 0.1 eV, but the T1 energy is hardly changed. The obtained reduction of ΔEST is crucial to effectively suppress triplet recombination and acquire small exciton dissociation driving force. Thus, end-group π?π stacking is an effective way to achieve both small energy loss and efficient light absorption for high-efficiency organic photovoltaics.
关键词： energy loss,triplet recombination,molecular packing,nonfullerene acceptors
更新于2025-09-23 15:19:57
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Nonfullerene acceptors with an N-annulated perylene core and two perylene diimide units for efficient organic solar cells
摘要： We have designed and synthesized a series of perylene based A-D-A type chromophores, which are composed of two electron deficient perylene diimides (PDI) and one electron rich N-annulated perylene (NP). By virtue of the bi-axial rigid skeleton of the flat NP unit, the intermolecular aggregation is efficiently suppressed, leading to a very small red-shift of absorption being observed in going from solutions to films. In addition, the molar extinction coefficients have been significantly elevated in case of sulfur or selenium annulation at the bay positions of the PDI units. Quantum calculation is employed for the geometry optimization to further understand the contributions of different excitations to the UV-vis absorption spectra. Morphology studies demonstrate that the twisted conformations of these acceptors are favorable for the formation of suitable phase separation in the as-cast films. The heteroatom annulation could force the PDI plane to take on a more planar conformation, which is favorable to have closer π?π stacking for efficient electron transportation. Finally, the as-cast devices based on PBDB-T:NP-diPDI-Se display a power conversion efficiency (PCE) of 6.25% with a Voc of 0.98 V, a Jsc of 11.73 mA/cm2 and an FF of 54.13%.
关键词： N-annulated perylene,Nonfullerene acceptors,Organic solar cells,Power conversion efficiency,Perylene diimide
更新于2025-09-19 17:13:59
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Ultrafast Hole Transfer and Carrier Transport Controlled by Nanoscale-Phase Morphology in Nonfullerene Organic Solar Cells
摘要： Nonfullerene acceptors (NFAs) have attracted great attention in high-efficiency organic solar cells (OSCs). While the effect of molecular properties including structures and energetics on charge transfer have been extensively investigated, the effect of macroscopic phase properties is yet to be revealed. Here we have performed a correlation study of the nanoscale phase morphology on photoexcited hole transfer (HT) process and photovoltaic performance, by combing ultrafast spectroscopy with high temporal resolution and photo-induced force microscopy (PiFM) with high spatial and chemical resolution. In PM6/IT-4F, we observe a biphasic HT behavior with a minor ultrafast (< 100 fs) interfacial process and a major diffusion mediated HT process till ~ 100 ps, which depends on phase segregation strongly. Because of the interplay between charge transfer and transport, a compromised domain size of 20 ~ 30 nm for NFAs shows best performance. This study highlights the critical role of phase morphology in high-efficiency OSCs.
关键词： photo-induced force microscopy,phase morphology,ultrafast spectroscopy,organic solar cells,hole transfer,Nonfullerene acceptors
更新于2025-09-19 17:13:59
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Trifluoromethylation Enables a 3D Interpenetrated Low-Band-Gap Acceptor for Efficient Organic Solar Cells
摘要： Herein, tri?uoromethylation has proven to be an effective strategy for ultra-narrow band-gap NFAs. A PCE of 15.59% is achieved from BTIC-CF3-g-based devices, which is the highest value in reported ultra-narrow band-gap acceptors. A ternary device with 16.50% ef?ciency is also obtained, resulting from its red-shifted absorption. Meanwhile, the single-crystal structure of BTIC-CF3-g has been successfully presented, which gives a deep understanding of the solid-state molecular packings in these highly ef?cient acceptors.
关键词： ultra-narrow band-gap,nonfullerene acceptors,tri?uoromethylation,power conversion efficiency,organic solar cells
更新于2025-09-19 17:13:59
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Bandgap Tailored Nonfullerene Acceptors for Low-Energy-Loss Near-Infrared Organic Photovoltaics
摘要： A series of A?π?D?π–A type nonfullerene acceptors (NFAs) was designed and synthesized with the goal of optimizing light absorption and energy losses in near-infrared (NIR) organic solar cells (OSCs) principally through the use of side chain engineering. Specific molecules include p-IO1, o-IO1, p-IO2, and o-IO2 with optical bandgaps of 1.34 eV, 1.28 eV, 1.24 eV, and 1.20 eV, respectively. Manipulating the optoelectronic properties and intermolecular organization by substituting bulky phenylhexyl (p-) for linear octyl chains (o-) and replacing bisalkoxy (-O2) with alkyl-alkoxy combination (-O1) allows one to target energy bandgaps and achieve a favorable bulk heterojunction morphology when in the presence of the donor polymer PTB7-Th. Solar cells based on o-IO1 and PTB7-Th exhibit an optimal power conversion efficiency of 13.1%. The excellent photovoltaic performance obtained with the o-IO1 acceptor can be attributed to a short-circuit current of 26.3 mA cm?2 and energy losses on the order of 0.54 eV. These results further highlight how side chain engineering is a straightforward strategy to tune the molecular design of n-type molecular semiconductors, particularly in the context of near-infrared high efficiency organic photovoltaics.
关键词： side chain engineering,nonfullerene acceptors,power conversion efficiency,organic solar cells,near-infrared
更新于2025-09-19 17:13:59
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Evaporation‐Free Nonfullerene Flexible Organic Solar Cell Modules Manufactured by An All‐Solution Process
摘要： To ensure laboratory-to-industry transfer of next-generation energy harvesting organic solar cells (OSCs), it is necessary to develop flexible OSC modules that can be produced on a continuous roll-to-roll basis and to apply an all-solution process. In this study, nonfullerene acceptors (NFAs)-based donor polymer, SMD2, is newly designed and synthesized to continuously fabricate high-performance flexible OSC modules. Also, multifunctional hole transport layers (HTLs), WO3/HTL solar bilayer HTLs, are developed and applied via an all-solution process called “ProcessOne” into inverted structure. SMD2, the donor terpolymer, has a deep highest occupied molecular orbital (HOMO) level and can achieve a power conversion efficiency (PCE) of 11.3% with NFAs without any pre-/post-treatment because of its optimal balance between crystallinity and miscibility. Furthermore, the integration of multifunctional HTLs enables the recovery of the drop in open circuit voltage (VOC) caused by a mismatch in energy levels between the deep HOMO level of the NFAs-based bulk-heterojunction layer and the solution-processed HTLs. Also, the photostability under ultraviolet-exposure necessary for “ProcessOne” is greatly improved because of the integration of multifunctional HTLs. Consequently, because of the synergistic effects of these approaches, the flexible OSC modules fabricated in an industrial production line have a PCE of 5.25% (Pmax = 419.6 mW) on an active area of 80 cm2.
关键词： roll-to-roll process,all-solution process,flexible modules,nonfullerene acceptors,organic solar cells
更新于2025-09-19 17:13:59
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Tunnel oxide passivating electron contacts for high‐efficiency n‐type silicon solar cells with amorphous silicon passivating hole contacts
摘要： Organic photovoltaics (OPVs) consisting of a wide bandgap polymer donor and a nonfullerene acceptor (NFA) have received attention because they can effectively overcome the weaknesses of efficiency and stability for fullerene-based OPVs. One of the NFAs, ITIC, shows an excellent power conversion efficiency, as well as controllable solubility, absorption, crystallinity, and energy level. Thus, high-efficiency OPVs could be achieved by developing polymer donors appropriate for use with ITIC-based OPVs. In this study, the synthesized polymer donor, PBDTT-8ttTPD, containing alkylthieno[3,2-b]thiophene as π-bridge and thieno[3,4-c]pyrrole-4,6(5H)-dione (ttTPD) shows strong absorption with a sharp peak edge at around 700 nm. In addition, the high hole mobility and face-on oriented polymer structures in the blend films make ttTPD the best candidate for the donor in NFA-based OPVs. Notably, the molecular weight of the face-on preferred polymer donor is crucial for determining the power conversion efficiency (PCE) of the NFA-based devices. A high molecular weight improves the π?π stacking ordering, absorption, and nanomorphology of the blend films, resulting in a dramatic PCE improvement from 5.76% to 11.05% compared with that of the fullerene-based OPV device (7.86%).
关键词： organic photovoltaics,nonfullerene acceptors,molecular weight,TPD-based polymer,wide band gap donnor polymer
更新于2025-09-19 17:13:59