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Designing indenothiophene-based acceptor materials with efficient photovoltaic parameters for fullerene-free organic solar cells
摘要： Non-fullerene small molecular acceptors (NFSMAs) exhibit promising photovoltaic performance which promoted the rapid progress of organic solar cells (OSCs). In this study, an attempt is done to explore indenothiophene-based high-performance small molecular electron acceptors for organic solar cells. We have designed five acceptor molecules (M1–M5) with strong donor moiety indenothiophene linked to five different end-capped group acceptor moieties: diflouro-2-methylene-3-oxo-2,3-dihydroindene-1-ylidene)malononitrile (A1), 1-(dicyanomethylene)-2-methylene-3-oxo-2,3-dihydro-1H-indene-5,6-dicarbonitrile (A2), methyl-6-cyano-3-(dicyanomethylene)-2-methylene-1-oxo-2,3-dihydro-1H-indene-5-carboylate (A3), 2-(6-cyano-5-fluoro-2-methylene-3-oxo-2,3 dihydro-1H-indene-1-ylidene)malononitrile (A4), and (Z)-methyl 3-(benzo [c][1,2,5]thiadiazol-4-yl)-2-cyanoacrylate (A5) respectively. The structure–property relationship was studied and effects of structural modification on the optoelectronic properties of these acceptors (M1–M5) were determined systematically by comparing it with reference molecule R, which is recently reported as excellent non-fullerene-based small acceptor molecule. Among all designed molecules, M5 is proven as a suitable candidate for organic solar cell applications due to better photovoltaic properties including narrow HOMO-LUMO energy gap (2.11 eV), smallest electron mobility (λe = 0.0038 eV), highest λmax values (702.82 nm in gas) and (663.09 nm in chloroform solvent) and highest open-circuit voltage (Voc = 1.49 V) with respect to HOMOPTB7-Th–LUMOacceptor. Our results indicate that introducing more end-capped electron-accepting units is a simple and effective alternative strategy for the design of promising NFSMAs. This theoretical framework also proves that the conceptualized NFSMAs are superior and thus are recommended for the future construction of high-performance organic solar cell devices.
关键词： Photovoltaic properties,Indenothiophene,Density functional theory (DFT),Non-fullerene acceptor materials,Organic solar cells (OSCs)
更新于2025-09-23 15:21:01
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The Balance between Energy Transfer and Exciton Separation in Ternary Organic Solar Cells with Two Conjugated Polymer Donor
摘要： Ternary strategy as a straightforward way for organic solar cells (OSCs) to improve the device performance attracts many interests in the field. The ternary strategy usually focuses on processing the third light-absorbing material owning a complementary absorption to the binary system. However, studying the third component with similar absorption spectra to the binary counterpart is equally essential to understand the in-depth mechanism of the performance improvement from the third component. In this work, we filled up this blank and derived a type of ternary device consisting of two conjugated polymer donor materials of PTB7-Th and PffBT4T-2OD and non-fullerene acceptor material of IEICO-4F. The average PCE value of the optimized ternary device reached 12.1%, which is around 16% higher than its PTB7-Th:IEICO-4F binary counterpart. Even the third component of PffBT4T-2OD containing a similar absorption spectrum with PTB7-Th, it was found that the Jsc increase contributes to the primary performance enhancement. Further investigations indicate that the Jsc increase in the optimized ternary device mainly came from the improved light absorption ability, current extraction process, charge transport process, and suppressed non-radiative recombination. Moreover, there is a balance found between the exciton separation process and the energy transfer process when optimizing ternary blend ratios. The optimized ternary device is suspected to reach this balance point and thus exhibits the enhancement in device performance. Morphology investigation reveals that the addition of PffBT4T-2OD can tune the morphology and increase the crystallinity in the active layer. The optimized ternary blend shows a well-mixed donor and acceptor morphology with small domain size and slightly increased crystallization, which further explained its best device performance.
关键词： non-fullerene,energy transfer,exciton separation,organic solar cells,ternary,crystallization,conjugated polymer
更新于2025-09-23 15:21:01
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Sa?ˉCl intramolecular interaction: An efficient strategy to improve power conversion efficiency of organic solar cells
摘要： Noncovalent conformational locks (NCLs) including S···N, Se···O, and S···O etc. have been an effective strategy to improve the planarity and rigidity, and charge transport mobility of organic/polymeric semiconductors. Herein, by replacing methyl group (ITMIC) with chlorine (ITCIC) in the π-bridge, the planarity and rigidity of the π-conjugated skeleton was enhanced by introduction of S···Cl NCLs, thus the charge transport mobility was improved accordingly. As a result, PM6:ITCIC based organic solar cells showed impressive PCE of 11.34%, much higher than that based on PM6:ITMIC. This contribution demonstrated a novel kind NCLs (S···Cl) for improving the performance of organic solar cells.
关键词： noncovalent conformational locks,organic solar cells,non-fullerene acceptor,charge transport mobility
更新于2025-09-23 15:21:01
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Flexible Organic Solar Cells Over 15% Efficiency with Polyimide-Integrated Graphene Electrodes
摘要： A highly flexible and durable transparent graphene electrode with thermal stability was developed via the direct integration of polyimide (PI) on graphene. Due to the high transparency of PI-integrated graphene electrode and intimate contact between graphene and PI substrate, high-efficiency flexible organic solar cell with a PCE of 15.2% and outstanding mechanical robustness was obtained.
关键词： Thermal Stability,High Efficiency,Polyimide-Integrated Graphene Electrodes,Flexible Organic Solar Cells,Mechanical Robustness
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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Effect of Solvent Additives on the Morphology and Device Performance of Printed Non-fullerene Acceptor Based Organic Solar Cells
摘要： Printing of active layers of high-efficiency organic solar cells and morphology control by processing with varying solvent additive concentrations are important to realize real-world use of bulk-heterojunction photovoltaics as it enables both, up-scaling and optimization of the device performance. In this work, active layers of the conjugated polymer with benzodithiophene units PBDB-T-SF and the non-fullerene small molecule acceptor IT-4F are printed using meniscus guided slot-die coating. 1,8-diiodoctane (DIO) is added to optimize the power conversion efficiency (PCE). The effect on the inner nano-structure and surface morphology of the material is studied for different solvent additive concentrations with grazing incidence small angle X-ray scattering (GISAXS), grazing incidence wide angle X-ray scattering (GIWAXS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Optical properties are studied with photoluminescence (PL), UV/Vis absorption spectroscopy and external quantum efficiency (EQE) measurements and correlated to the corresponding PCEs. The addition of 0.25 vol% DIO enhances the average PCE from 3.5 to 7.9 % whereas at higher concentrations the positive effect is less pronounced. A solar cell performance of 8.95 % is obtained for the best printed device processed with an optimum solvent additive concentration. Thus, with the large-scale preparation method printing similarly well working solar cells can be realized as with the spin-coating method.
关键词： slot-die coating,solvent additives,small molecule acceptor,high-efficiency organic solar cells,printed organic solar cells
更新于2025-09-23 15:19:57
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Constructing Higha??Performance Organic Photovoltaics via Emerging Nona??Fullerene Acceptors and Tandema??Junction Structure
摘要： In consideration of the unique advantages of new non-fullerene acceptors and the tandem-junction structure, organic photovoltaics (OPVs) based on them are very promising. Studies related to this emerging area began in 2016 with achieved power conversion efficiencies (PCEs) of 8–10%, which have now been boosted to 17%. In this essay, the construction of high-performance OPVs is discussed, with a focus on combining the advantages of new non-fullerene acceptors and the tandem-junction structure. In order to achieve higher PCEs, methods to enable high short-circuit current density, open-circuit voltage, and fill factor are discussed. In addition, the stability and reproducibility of high-efficiency OPVs are also addressed. Herein, it is forecast that the new non-fullerene acceptors-based tandem-junction OPVs will become the next big wave in the field and achieve high PCEs over 20% in the near future. Some promising research directions on this emerging hot topic are proposed which may further push the field into the 25% high efficiency era and considerably advance the technology beyond laboratory research.
关键词： non-fullerene acceptors,organic solar cells,organic photovoltaics,tandem solar cells
更新于2025-09-23 15:19:57
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An efficient medium-bandgap nonfullerene acceptor for organic solar cells
摘要： A medium-bandgap acceptor IBCT based on an 2-(1-oxo-1,2-dihydro-3H-benzo[b]cyclopenta[d]thiophen-3-ylidene)malononitrile end unit was developed. IBCT has an optical bandgap of 1.65 eV and afforded a power conversion efficiency of 11.26% and an open-circuit voltage of 1.02 V in single-junction organic solar cells when blending with a wide-bandgap copolymer donor L1. The L1:IBCT solar cell was further used as the front cell in tandem solar cells, yielding a 15.25% efficiency. IBCT is among the best medium-bandgap acceptors.
关键词： organic solar cells,medium-bandgap acceptor,tandem solar cells,power conversion efficiency
更新于2025-09-23 15:19:57
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Delayed Fluorescence Emitter Enables Near 17% Efficiency Ternary Organic Solar Cells with Enhanced Storage Stability and Reduced Recombination Energy Loss
摘要： Charge transfer state (CT) plays an important role in exciton diffusion, dissociation, and charge recombination mechanisms. Enhancing the utilization and suppressing the recombination process of CT excitons is a promising way to improve the performance of organic solar cells (OSCs). Here, an effective method is presented via introducing a delayed fluorescence (DF) emitter 3,4-bis(4-(diphenylamino)phenyl) acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile (APDC-TPDA) in OSCs. The long-lifetime singlet excitons on APDC-TPDA can transfer to polymer donors to prolong exciton lifetime, which ensures sufficient time for diffusion and dissociation. Concurrently, the high triplet energy level (T1) of the DF material can also prevent the reverse energy transfer from CT to T1. APDC-TPDA-containing ternary OSCs shows a high PCE of 16.96% with a reduced recombination energy loss of 0.46 eV. It is noteworthy that the ternary OSC also exhibits superior storage stability. After 55 days of storage, the PCE of the ternary OSC still retains about 96% of its primitive state. Furthermore, this ternary strategy is efficient and universally applicable to OSCs, and positive results can be obtained in different systems with different DF emitters. These results indicate that the ternary strategy provides a new design idea to realize high performance OSCs.
关键词： delayed fluorescence,recombination energy loss,organic solar cells,charge transfer state,storage stabile solar cells
更新于2025-09-23 15:19:57
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Enhanced Efficiency and Stability of Nonfullerene Ternary Polymer Solar Cells Based on Spontaneously Assembled Active Layer: The Role of a High Mobility Small Molecular Electron Acceptor
摘要： It is challenging to afford efficient and stable organic solar cells based on the as-cast active layer without any external treatments. We present a planar organic electron acceptor BPTCN with high electron mobility as a third component in nonfullerene ternary polymer solar cells, which comprises an electron-deficient 4,7-bis(5H-4,6-dioxothieno[3,4-c]pyrrol-1-yl)benzo[c][1,2,5]thiadiazole core, doubly endcapped by 2-(3-ethyl-5-methylene-4-oxothiazolidin-2-ylidene)malononitrile through the alkylated thiophene-2,5-ylene unit. It shows a π-π stacking distance of 3.60 ? and μe of 1.31 × 10?3 cm2 V?1 s?1. BPTCN exhibits an absorption maximum at 569 nm in the as-cast film and good miscibility with the NIR-absorption acceptor COi8DFIC, leading to complete f?rster energy transfer in the blends. Adding BPTCN into the PTB7-Th:COi8DFIC blend produces multiple beneficial effects: i) facilitating exciton dissociation and charge transfer at the donor/acceptor interface while suppressing bimolecular and trap-assisted recombination by analysis of the Jph–Veff, Jsc–Ilight and Voc–Ilight characteristics, ii) increasing hole and in particular electron transport; and iii) generally promoting the crystallinity of the polymer donor PTB7-Th, as revealed by grazing incidence X-ray diffraction. Moreover, the phase purity is greatly improved in the ternary blend PTB7-Th:COi8DFIC:BPTCN (1:1.05:0.45 by weight). Consequently, the tentatively optimized ternary solar cell provides a PCE of 11.62% with Voc = 0.74 V, Jsc = 25.93 mA cm-2 and FF = 60.61% in comparison with the binary systems PTB7-Th:COi8DFIC (PCE of 9.41%) and PTB7-Th:BPTCN (6.42%) in the absence of any extra treatments. After thermal aging at 80 oC for 450 h, this ternary solar cell exhibits increased stability with PCE retaining 84.39% of the initial value.
关键词： PTB7-Th,COi8DFIC,BPTCN,electron acceptor,organic solar cells,thermal stability,nonfullerene ternary polymer solar cells
更新于2025-09-23 15:19:57