- 标题
- 摘要
- 关键词
- 实验方案
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Molecular vibrations reduce the maximum achievable photovoltage in organic solar cells
摘要： The low-energy edge of optical absorption spectra is critical for the performance of solar cells, but is not well understood in the case of organic solar cells (OSCs). We study the microscopic origin of exciton bands in molecular blends and investigate their role in OSCs. We simulate the temperature dependence of the excitonic density of states and low-energy absorption features, including low-frequency molecular vibrations and multi-exciton hybridisation. For model donor-acceptor blends featuring charge-transfer excitons, our simulations agree very well with temperature-dependent experimental absorption spectra. We unveil that the quantum effect of zero-point vibrations, mediated by electron-phonon interaction, causes a substantial exciton bandwidth and reduces the open-circuit voltage, which is predicted from electronic and vibronic molecular parameters. This effect is surprisingly strong at room temperature and can substantially limit the OSC’s efficiency. Strategies to reduce these vibration-induced voltage losses are discussed for a larger set of systems and different heterojunction geometries.
关键词： molecular vibrations,exciton bands,electron-phonon interaction,organic solar cells,photovoltage
更新于2025-09-23 15:19:57
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3a??Dimensional Charge Transport Pathway in Organic Solar Cells via Incorporation of Discotic Liquid Crystal Columns
摘要： 2,3,6,7,10,11-hexaacetoxytriphenylene (HATP) as a discotic liquid crystals with high mobility can aggregate into columns structure on PEDOT:PSS in organic solar cells. HATP columns facilitate the formation of 3-dimensional charge transport pathway, which increase the intermolecular charge transport and mobility. Additionally, the triplet exciton, trap state and bimolecular recombination is suppressed. Thus, the JSC is increased significantly for (non-) fullerene system.
关键词： discotic liquid crystal,organic solar cells,mobility,columnar structure,3-dimensional charge transport
更新于2025-09-23 15:19:57
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15.3% efficiency all-small-molecule organic solar cells enabled by symmetric phenyl substitution; ???????ˉ1?§°??§è?ˉ??o???é￥°?????°??????é??è??15.3%?????¨?°? ????-??????o?¤aé?3è????μ?±?;
摘要： Synergistic optimization of donor-acceptor blend morphologyis a hurdle in the path of realizing efficient non-fullerene small-molecule organic solar cells (NFSM-OSCs) due to the anisotropic conjugated backbones of both donor and acceptor. Therefore, developing a facile molecular design strategy to effectively regulate the crystalline properties of photoactive materials, and thus, enable the optimization of blend morphology is of vital importance. In this study, a new donor molecule B1, comprising phenyl-substituted benzo-dithiophene (BDT) central unit, exhibits strong interaction with the non-fullerene acceptor BO-4Cl in comparison with its corresponding thiophene-substituted BDT-based material, BTR. As a result, the B1 is affected and induced from an edge-on to a face-on orientation by the acceptor, while the BTR and the acceptor behave individually for the similar molecular orientation in pristine and blend films according to grazing incidence wide angle X-ray scattering results. It means the donor-acceptor blend morphology is synergistically optimized in the B1 system, and the B1:BO-4Cl-based devices achieve an outstanding power conversion efficiency (PCE) of 15.3%, further certified to be 15.1% by the National Institute of Me-trology, China. Our results demonstrate a simple and effective strategy to improve the crystalline properties of the donor molecule as well as synergistically optimize the morphology of the all-small-molecule system, leading to the high-performance NFSM-OSCs.
关键词： all-small-molecule,intermolecular interaction,crystallinity,organic solar cells,non-fullerene
更新于2025-09-23 15:19:57
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Simultaneously improving the photovoltaic parameters of organic solar cells <i>via</i> isomerization of benzo[ <i>b</i> ]benzo[4,5]thieno[2,3- <i>d</i> ]thiophene-based octacyclic non-fullerene acceptors
摘要： Fused-ring electron acceptors (FREAs) have attracted immense interest owing to their ability for facile structural modification and good thermal and optical characteristics. Among these acceptors, isomerized building blocks originate from multiple reaction sites affect the electronic structures, morphological properties and resulting photovoltaic performance, but have rarely been studied. Herein, three isomeric FREAs, Z1-aa, Z1-ab, and Z1-bb, were synthesized using different reaction sites of benzo[b]benzo[4,5]thieno[2,3-d]thiophene (BTBT)-based fused-ring cores and were used in organic solar cells (OSCs). As compared to Z1-aa and Z1-ab, Z1-bb exhibited red-shifted absorption and a higher maximum molar extinction coefficient. When blended with PM6, Z1-bb-based OSCs exhibited more balanced charge transport compared to those with the PM6:Z1-aa and PM6:Z1-ab blend films, which favored higher short-circuit current density (Jsc) and fill factor (FF). As a result, the OSC devices based on Z1-bb exhibited a power conversion efficiency (PCE) of 12.66% with Voc = 0.98 V, Jsc = 18.52 mA cm-2, and FF = 70.05%, respectively, which are significantly higher than the values recorded for Z1-ab-based (PCE of 9.60%)?and Z1-aa-based (PCE of 4.56%) devices. These results indicate that the isomerization of a fused-ring core originating from a special reaction site could be a promising approach to achieve high-performance OSCs with high Jsc, Voc, and FF.
关键词： Organic solar cells,Isomerization,Fused-ring electron acceptors,BTBT-based fused-ring cores,Photovoltaic performance
更新于2025-09-23 15:19:57
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Flexible Alla??Solutiona??Processed Organic Solar Cells with Higha??Performance Nonfullerene Active Layers
摘要： All-solution-processed organic solar cells (from the bottom substrate to the top electrode) are highly desirable for low-cost and ubiquitous applications. However, it is still challenging to fabricate efficient all-solution-processed organic solar cells with a high-performance nonfullerene (NF) active layer. Issues of charge extraction and wetting are persistent at the interface between the nonfullerene active layer and the printable top electrode (PEDOT:PSS). In this work, efficient all-solution-processed NF organic solar cells (from the bottom substrate to the top electrode) are reported via the adoption of a layer of hydrogen molybdenum bronze (HXMoO3) between the active layer and the PEDOT:PSS. The dual functions of HXMoO3 include: 1) its deep Fermi level of ?5.44 eV can effectively extract holes from the active layer; and 2) the wetting issues of the PEDOT:PSS on the hydrophobic surface of the NF active layer can be solved. Importantly, fine control of the HXMoO3 composition during the synthesis is critical in obtaining processing orthogonality between HXMoO3 and the PEDOT:PSS. Flexible all-solution-processed NF organic solar cells with power conversion efficiencies of 11.9% and 10.3% are obtained for solar cells with an area of 0.04 and 1 cm2, respectively.
关键词： nonfullerene organic solar cells,all-solution-processed,hydrogen molybdenum bronze,charge extraction,wetting
更新于2025-09-23 15:19:57
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Over 14% Efficiency Folding-Flexible ITO-free Organic Solar Cells Enabled by Eco-friendly Acid-Processed Electrodes
摘要： Environment-friendly manufacturing and mechanical robustness are imperative for commercialization of flexible OSCs as green-energy source, especially in portable and wearable self-powered flexible electronics. Although, the commonly adopted PEDOT:PSS electrodes that are treated with severely corrosive and harmful acid lack foldability. Herein, efficient folding-flexible OSCs with highly conductive and foldable PEDOT:PSS electrodes processed with eco-friendly cost-effective acid and polyhydroxy compound are demonstrated. The acid treatment endows PEDOT:PSS electrodes with high conductivity. Meanwhile, polyhydroxy compound doping contributes to excellent bending flexibility and foldability due to the better film adhesion between PEDOT:PSS and PET substrate. Accordingly, folding-flexible OSCs with high efficiency of 14.17% were achieved. After 1,000 bending or folding cycles, the device retained over 90% or 80% of its initial efficiency, respectively. These results represent one of the best performances for ITO-free flexible OSC reported so far and demonstrate a novel approach toward commercialized efficient and foldable green-processed OSCs.
关键词： high efficiency,flexible organic solar cells,foldability,PEDOT:PSS,eco-friendly acid
更新于2025-09-23 15:19:57
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Introducing Trifluoromethyl to Strengthen Hydrogen Bond for High Efficiency Organic Solar Cells
摘要： Nowadays, the ternary strategy has become a common way to improve the power conversion efficiency (PCE) of organic solar cells (OSCs). The intermolecular interaction between the third component and donor or acceptor plays a key role in achieving a high performance. However, hydrogen bond as a strong intermolecular interaction is rarely considered in ternary OSCs. In this work, we introduce trifluoromethyl on a newly synthesized small molecular DTBO to strength hydrogen bonds between DTBO and IEICO-4F. Due to the existence of hydrogen bonds has a strong impact on electrostatic potential (ESP) and benefits π-π stacking in the active layer, the ternary OSCs show superior charge extraction and low charge recombination. In DTBO, PTB7-Th and IEICO-4F based ternary devices, the PCE increases from 11.02 to 12.48%, and short-circuit current density (JSC) increases from 24.94 to 26.43 mA/cm2 compared with typical binary devices. Moreover, the addition of DTBO can realize an energy transfer from DTBO to PTB7-Th and broaden the absorption spectrum of blend films. Grazing-incidence wide-angle X-ray scattering (GIWAXS) patterns show that the π-π stacking distance of IEICO-4F decreased after adding 10 wt% DTBO. The effect of the hydrogen bond is also achieved in the PM6: Y6 system, showing 16.64% efficiency by comparison to the 15.49% efficiency of binary system. This work demonstrates that introduce trifluoromethyl to enhance hydrogen bond which improve π-π stacking can achieve higher performance in OSCs.
关键词： energy transfer,ternary devices,organic solar cells,hydrogen bond,π-π stacking
更新于2025-09-23 15:19:57
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The Role of Dipole Moment in Two Fused-Ring Electron Acceptors with One Polymer Donor based Ternary Organic Solar Cells
摘要： Fused-ring electron acceptors (FREAs) based ternary organic solar cells (OSCs) have made significant progress and attracted considerable attention due to their simple device architecture and broad absorption range in devices. There are three key parameters that need to be fine-tuned in ternary OSCs including absorption, energy level and morphology in order to realize high efficiencies. Herein, a series of FREAs with diverse electron-rich cores or electron-deficient terminals are developed and rationally combined to achieve high performance ternary OSCs. A new factor of dipole moment of FREAs’ terminals is unveiled and its working mechanism has been thoroughly investigated by systematical studying of six ternary OSCs. These ternary blends all exhibit complementary absorptions and cascade energy levels, which can facilitate efficient light-harvesting and charge transfer. Additionally, the morphological effects on ternary OSCs are eliminated through comparative studies while demonstrating distinctively different performance. The preliminary results show that compatible dipole moment between two FREAs is critical in ternary blends. Specifically, the performance of the ternary system with two FREAs having quite different dipole moment terminals is worse than that with similar terminal dipole moments. The pair with larger difference in dipole moment will also negatively impact device performance. This interesting phenomenon is likely due to that very different dipole moments of terminals in FREAs can significantly decrease the electron mobility as well as induce unbalanced hole/electron transport. Consequently, it results in increased charge recombination and reduced charge collection efficiency. This finding demonstrates that dipole moment of FREAs should be taken into account in designing ternary OSCs.
关键词： ternary organic solar cells,morphology,dipole moment,charge transfer,Fused-ring electron acceptors
更新于2025-09-23 15:19:57
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Asymmetrically noncovalently fused-ring acceptor for high-efficiency organic solar cells with reduced voltage loss and excellent thermal stability
摘要： Simultaneously broadening the spectral response and reducing the energy loss are challenging tasks in the material design of organic solar cells (OSCs). Herein, a novel asymmetrically noncovalently fused-ring electron acceptor (NFEA) with unilateral alkylthio-substituted thiophene π-bridge, namely IDST-4F, is synthesized. IDST-4F exhibits a broader absorption, higher-lying energy levels, larger dipole moments and suppressed crystallinity than its symmetric counterpart (ID-4F) without the π-bridge. Compared to the devices of PM6:ID-4F, the optimized PM6:IDST-4F-based devices display simultaneously enhanced current density and photovoltage, resulting in an excellent power conversion efficiency (PCE) of 14.3%, which is the highest value among the OSCs based on NFEAs reported in the literature to date. More importantly, the PM6:IDST-4F-based OSCs possess excellent thermal stability with 82% of the initial PCE after thermal treatment at 150 °C for 1200 min. In summary, this study indicates that asymmetrically NFEAs are promising to achieve high efficiency with excellent thermal stability.
关键词： Organic solar cells,Noncovalently fused rings,Thermal stability,Narrow-bandgap acceptor,Energy loss
更新于2025-09-23 15:19:57
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Comparative study of conventional and inverted P3HT: PCBM organic solar cell
摘要： This work is a comprehensive comparative study between conventional and inverted bulk hetero-junction (BHJ) Organic Solar Cell (OSC and IOSC) using GPVDM software. Contrary to conventional OSCs with a low work-function cathode located on the top, IOSC is characterized by a bottom transparent conductive oxide cathode. The calculated current-voltage characteristic (J-V) is used to extract the main electrical outputs (figures of merit) of the solar cell: the short circuit current (Jsc), the open circuit voltage (Voc), the fill factor (FF) and the efficiency (η). The effect of a number of physical parameters is studied including thickness of the different layers and materials used as electron (hole) transport layer, ETL (HTL). In addition, different top and bottom electrodes are suggested with mono and multi-thin layer. A comparison between the effect of all these factors in OSC and IOSC is also performed and it was found that IOSC using multi-thin layer ATZ (AZO/TiOx/ZnO) as bottom contact gives the best efficiency of 5.46% in comparison with 5.02% obtained for the conventional OSC with ZnO/TiOx/ZnO contact.
关键词： Organic solar cells,Inverted structure,Bulk hetero-junction,GPVDM Software,Multi-thin layer electrodes
更新于2025-09-23 15:19:57