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Recent Progress in Chlorinated Organic Photovoltaic Materials
摘要： Over the past few years, the development of new materials has contributed to rapid increases in the power conversion efficiencies (PCEs) of organic photovoltaic (OPV) cells to over 17%, showing great potential for the commercialization of this technology in the near future. At this stage, designing new materials with superior performance and low cost simultaneously is of crucial importance. Chlorinated materials are emerging as new stars with very high PCEs, creating a molecular design trend to replace the most popular fluorinated materials. For example, by using chlorinated non-fullerene acceptors, we recently got a record PCE of 17% for single-junction OPV cells. Firmly based on recent advances, herein we focus on the topic of chlorinated OPV materials, aiming to provide a guideline for further molecular design.
关键词： chlorinated materials,organic photovoltaic cells,power conversion efficiencies,non-fullerene acceptors,molecular design
更新于2025-09-23 15:19:57
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Enhanced performance of P3HT-based non-fullerene polymer solar cells by optimizing film morphology using non-halogenated solvent
摘要： Increasing research interests have been paid to developing efficient polymer solar cells by using integrating non-fullerene acceptors with poly(3-hexylthiophene) (P3HT), owing to the low-cost, promising performance and excellent stability. Here we systematically studied how processing solvents influence the overall performances of polymer solar cells using P3HT as the electron donor. It is very interesting to note that the devices processed with the non-halogenated solvent, 2-methylanisole in presence of 1-methylnaphthalene as solvent additive, exhibit reduced bimolecular and trap-assisted monomolecular recombination, facile charge extraction and enhanced charge carrier mobilities. Careful morphological investigation revealed that the optimizing crystallites, phase purity as well as nanofibrous structure is effective to the enhancement of charge generation and transport. It is also worth noting that these P3HT:O-IDTBR based devices processed with these non-halogenated solvents exhibited an impressive power conversion efficiency of 7.1% with a high fill factor of 75.09% on a device area of 0.05 cm2, and the efficiency remained 6.89% even in a device with large active layer area of 1 cm2, while also showing promising thermal stability. This study provides a new scope of processing P3HT based polymer solar cells by using non-halogenated solvents, which is compatible and has great promise for future applications.
关键词： large-area,polymer solar cell,poly(3-hexylthiophene),non-halogenated solvent,non-fullerene
更新于2025-09-19 17:13:59
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Efficient and Photostable Ternary Organic Solar Cells with a Narrow Bandgap Non-Fullerene Acceptor and Fullerene Additive
摘要： Recent breakthroughs in molecular design have allowed for remarkable achievement in the field of non-fullerene acceptor (NFA)-based organic solar cells (OSCs) with high power conversion efficiencies (PCEs) of over 15%. However, despite such promising advances, the inferior stability of OSCs under operational conditions remains a prominent challenge that must be overcome for their practical realization. Here, versatile ternary photoactive systems with simultaneously enhanced efficiency and photostability are developed by introducing a small amount of fullerene (PC71BM) into a narrow bandgap NFA-based bulk heterojunction nanocomposite (PTB7-Th:IEICO-4F); this approach leads to an enhanced PCE of 10.55% and a prolonged lifetime, retaining approximately 80% of the initial PCEs after 500 h of operation under continuous illumination. Based on the energy levels and surface energies of the component materials, cascade energetic alignment facilitates electron transfer without trapping. The PTB7-Th/PC71BM interface provides an energy barrier to suppress recombination between holes in PTB7-Th and electrons in IEICO-4F. Moreover, a small amount of PC71BM promotes favorable molecular packing and orientation of IEICO-4F, leading to enhanced electron mobility and balanced charge transport. The study on the transient absorption spectroscopy reveals that the ternary blend effectively suppresses the evolution of charge recombination.
关键词： photostability,non-fullerene acceptor,power conversion efficiency,organic solar cells,ternary blend
更新于2025-09-19 17:13:59
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Efficient Modulation of End Groups for the Asymmetric Small Molecule Acceptors Enabling Organic Solar Cells with over 15% Efficiency
摘要： Non-fullerene organic solar cells (OSCs) have attracted tremendous interest and made an impressive breakthrough, largely due to advances in high-performance small molecule acceptors (SMAs). The relationship between short-circuit current density (JSC) and open-circuit voltage (VOC) is usually shown as one falls and another rises. Controlling the trade-off between JSC and VOC to harvest high power conversion efficiencies (PCEs) still remains as a challenge. Herein, dithieno[3,2-b:2?,3?-d]pyrrole (DTP) based asymmetric SMAs with different chlorinated dicyanoindanone-based end groups, named TPIC, TPIC-2Cl and TPIC-4Cl, are designed and synthesized. These asymmetric acceptors exhibit remarkable red-shifted absorption profile, while energy levels are simultaneously down-shifted when the numbers of chlorine atoms alter from 0, 1 to 2, due to the gradually improved electronegativity. As a result, PM7: TPIC-4Cl based OSCs achieved a champion PCE of 15.31%, which is the highest PCEs for non-fullerene binary OSCs based on asymmetric SMAs. The superiority of PM7: TPIC-4Cl system consists of the balanced charge transport, favorable phase separation, efficient exciton dissociation and extraction, coupled with remarkable π–π stacking and crystallinity of the SMAs. Our results highlight the important strategy of asymmetric molecular design to optimize the trade-off between VOC and JSC, reaching a high PCE.
关键词： asymmetric molecular design,small molecule acceptors,chlorinated dicyanoindanone-based end groups,Non-fullerene organic solar cells,power conversion efficiencies
更新于2025-09-19 17:13:59
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Thieno[2,3-f]benzofuran based donor-acceptor polymer for fullerene-free solar cells
摘要： A donor–acceptor (D–A) polymer, PTBFDO-BDD, based on thieno[2,3-f]benzofuran (TBF) with 4-dodecyl thienyl chains, was designed and synthesized. The optical, electrochemical, photovoltaic and device active layer morphology properties of the new polymer were investigated. With the structure of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/PTBFDO-BDD:ITIC/PDINO/Al, polymer solar cells device exhibited a power conversion efficiency (PCE) of 7.15% (AM1.5G, 100 mW cm?2) with VOC of 0.803 V, JSC of 14.71 mA cm?2, and FF of 60.57%. This work demonstrates that thieno[2,3-f]benzofuran-based conjugated polymers are promising as polymer solar cells donor materials.
关键词： Non-fullerene acceptor,Polymer solar cells,Thieno[2,3-f]benzofuran
更新于2025-09-19 17:13:59
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Significant influence of the benzothiophene ring substitution position on the photovoltaic performance of benzodithiophene-based donor polymers
摘要： In order to investigate the e?ects of the substitution position on the photovoltaic performance of donor polymers, two benzothiophene ring substituted benzo(1,2-b:4,5-b0)dithiophene (BDT)-based conjugated polymers (PBDTBTs-BDD and PBDTTBs-BDD) are designed and synthesized. The variation in the substitution position has small influences on the photophysical properties but has a great e?ect on the intramolecular p–p stack structure, charge transport and photovoltaic properties. PBDTBTs-BDD (with the 6-position of the benzothiophene substituent) exhibited a smaller p–p stacking distance of 3.67 ? compared to 4.11 ? seen for PBDTTBs-BDD (with the 2-position of the benzothiophene substituent). And the charge mobilities of PBDTBTs-BDD-based devices are higher and more balanced than those of PBDTTBs-BDD-based devices, which are highly beneficial for reducing recombination of free carriers and then lead to a higher short-circuit current density (JSC) and fill factor (FF) of devices. With ITIC or Y6 as non-fullerene acceptors, PBDTBTs-BDD-based devices exhibit power conversion efficiencies (PCE) of 7.76% and 12.07%, respectively, which are higher than those of PBDTTBs-BDD-based devices (5.04% and 5.81%). This work demonstrates that the photovoltaic properties of donor polymers can be highly tunable through slight modifications of their side chain structures.
关键词： benzothiophene,donor polymers,photovoltaic performance,power conversion efficiencies,non-fullerene acceptors
更新于2025-09-19 17:13:59
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Improvement of Exciton Collection and Light-Harvesting Range in Ternary Blend Polymer Solar Cells Based on Two Non-Fullerene Acceptors
摘要： A non‐fullerene molecule named Y6 was incorporated into a binary blend of PBDB‐T and IT‐M to further enhance photon harvesting in the near‐infrared (near‐IR) region. Compared with PBDB‐T/IT‐M binary blend devices, PBDB‐T/IT‐M/Y6 ternary blend devices exhibited an improved short‐circuit current density (JSC) from 15.34 to 19.09 mA cm?2. As a result, the power conversion efficiency (PCE) increased from 10.65% to 12.50%. With an increasing weight ratio of Y6, the external quantum efficiency (EQE) was enhanced at around 825 nm, which is ascribed to the absorption of Y6. At the same time, EQE was also enhanced at around 600–700 nm, which is ascribed to the absorption of IT‐M, although the optical absorption intensity of IT‐M decreased with increasing weight ratio of Y6. This is because of the efficient energy transfer from IT‐M to Y6, which can collect the IT‐M exciton lost in the PBDB‐T/IT‐M binary blend. Interestingly, the EQE spectra of PBDB‐T/IT‐M/Y6 ternary blend devices were not only increased but also red‐shifted in the near‐IR region with increasing weight ratio of Y6. This finding suggests that the absorption spectrum of Y6 is dependent on the weight ratio of Y6, which is probably due to different aggregation states depending on the weight ratio. This aggregate property of Y6 was also studied in terms of surface energy.
关键词： non‐fullerene,exciton harvesting,surface energy,ternary blend solar cells,energy transfer
更新于2025-09-19 17:13:59
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Elucidating Roles of Polymer Donor Aggregation in All-Polymer and Non-Fullerene Small-Moleculea??Polymer Solar Cells
摘要： The aggregation behavior of polymers plays a crucial role in determining the optical, electrical, and morphological properties of donor-acceptor blends in both all-polymer solar cells (all-PSCs) and non-fullerene small molecule acceptor-polymer solar cells (NFSMA-PSCs). However, direct comparison of the impacts on two different systems has not been reported, although it is important to design universal polymer donors (PDs). Herein, three PDs with different side chains (P-EH, P-SEH and P-Si) are designed to study the PD aggregation effects on the blend morphology and device performance of both all-PSCs and NFSMA-PSCs. It is observed that the aggregation property of PDs is a critical factor in determining the optimal blend morphologies and ultimately the device performances in both the PSC systems. Furthermore, PD aggregation effects on device performance is significantly more impactful in all-PSCs than in NFSMA-PSCs. The P-Si PD exhibiting the strongest aggregation behavior in a processing solvent produces the most severe phase separation in the blend with a polymer acceptor, resulting in the lowest power conversion efficiency (PCE) of all-PSCs. In contrast, when P-Si is used in an NFSMA-PSC, a well-mixed blend morphology is observed, which results in the highest PCE of over 12%. These different roles dependent on PD aggregation mainly originate from the difference in molecular size of polymer acceptor and small molecule acceptor, which influences the entropic contribution to the formation of blend morphology. Our work provides a comprehensive understanding on the PD aggregation-blend morphology relationship in different all-PSC and NFSMA-PSC systems, which serves as an important guideline for the design of universal PDs for both all-PSCs and NFSMA-PSCs.
关键词： polymer solar cells,all-polymer solar cells,non-fullerene small molecule acceptor-polymer solar cells,polymer donor aggregation,blend morphology,power conversion efficiency
更新于2025-09-19 17:13:59
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Alkyl Chain Tuning of Small Molecule Acceptors for Efficient Organic Solar Cells
摘要： A new non-fullerene acceptor, named N3, was developed by using a 3rd-position branched alkyl chain on the pyrrole motif of the molecule, which yielded better performance than the state-of-the-art acceptor Y6. Ternary devices were fabricated, achieving a power conversion efficiency of 16.74% in the lab and a certified efficiency of 16.42% by Newport.
关键词： power conversion efficiency,ternary strategy,non-fullerene acceptor,alkyl chain tuning,organic solar cells
更新于2025-09-19 17:13:59
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Asymmetric 9,9a?2-bifluorenylidene-based small molecules as the non-fullerene acceptors for organic photovoltaic cells
摘要： Three new asymmetric 9,9'-bifluorenylidene-based derivatives, 2,7-dibutoxyl-3',6'-bis(5-methylenemalononitrile-3-octylthiophen-2-yl)-9,9'-bifluorenylidene (BF-TDCN2), 2,7-dibutoxyl-3',6'-bis(5-(methylene-indene-1,3-dione)-3-octylthiophen-2-yl)-9,9'-bifluorenylidene (BF-TID2) and 2,7-dibutoxyl-3',6'-bis(5-(2-methylene-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile)-3-octylthiophen-2-yl)-9,9'-bifluorenylidene (BF-TDCI2), were successfully synthesized by grafting different electron-withdrawing groups (malononitrile (DCN), 1H-indene-1,3(2H)-dione (ID) and 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (DCI)), which were used as the electron acceptors for organic photovoltaic cells. By changing the electron-withdrawing ability of the terminal group, the molecular energy level and band gap can be easily adjusted. The optical bandgaps of the three compounds in the thin films decreased with increasing the electron-withdrawing ability of the terminal group. Besides, the lateral chains of alkoxy groups located at the asymmetric end also play a certain influence on the solubility, molecular aggregation and the miscibility with polymer donor. Among these electron acceptors, the photovoltaic cell fabricated PBDB-T:BF-TDCI2 exhibited a maximum power conversion efficiency of 4.85% with an open-circuit voltage of 0.88 V and a low energy loss of 0.62 eV. By investigating different processing processes, the results showed that the power conversion efficiency can be improved by 20% with simple solvent annealing treatment. Through further study on the morphology and photophysical properties of the active layers, it was found that the processed device had better phase separation size and morphology, which was favorable to enhancing the intermolecular interaction, thus improving exciton separation and charge transfer in the active layer.
关键词： Non-fullerene acceptor,Organic photovoltaic cell,9,9'-bifluorenylidene derivative,Asymmetric molecule
更新于2025-09-19 17:13:59