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Highly efficient organic photovoltaics with enhanced stability through the formation of doping-induced stable interfaces
摘要： Flexible organic photovoltaics (OPVs) are promising power sources for wearable electronics. However, it is challenging to simultaneously achieve high efficiency as well as good stability under various stresses. Herein, we demonstrate the fabrication of highly efficient (efficiency, 13.2%) and stable OPVs based on nonfullerene blends by a single-step postannealing treatment. The device performance decreases dramatically after annealing at 90 °C and is fully recovered after annealing at 150 °C. Glass-encapsulated annealed OPVs show good environmental stability with 4.8% loss in efficiency after 4,736 h and an estimated T80 lifetime (80% of the initial power conversion efficiency) of over 20,750 h in the dark under ambient condition and T80 lifetime of 1,050 h at 85 °C and 30% relative humidity. This environmental stability is enabled by the synergetic effect of the stable morphology of donor/acceptor blends and thermally stabilized interfaces due to doping. Furthermore, the high efficiency and good stability are almost 100% retained in ultraflexible OPVs and minimodules which are mechanically robust and have long-term operation capability and thus are promising for future self-powered and wearable electronics.
关键词： nonfullerene acceptor,environmental stability,ultraflexible devices,organic photovoltaics,high efficiency
更新于2025-09-19 17:13:59
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Property Prediction of Organic Donor Molecules for Photovoltaic Applications Using Extremely Randomized Trees
摘要： Organic solar cells are an inexpensive, flexible alternative to traditional silicon-based solar cells but disadvantaged by low power conversion efficiency due to empirical design and complex manufacturing processes. This process can be accelerated by generating a comprehensive set of potential candidates. However, this would require a laborious trial and error method of modeling all possible polymer configurations. A machine learning model has the potential to accelerate the process of screening potential donor candidates by associating structural features of the compound using molecular fingerprints with their highest occupied molecular orbital energies. In this paper, extremely randomized tree learning models are employed for the prediction of HOMO values for donor compounds, and a web application is developed. The proposed models outperform neural networks trained on molecular fingerprints as well as SMILES, as well as other state-of-the-art architectures such as Chemception and Molecular Graph Convolution on two datasets of varying sizes.
关键词： Cheminformatics,Machine Learning,Organic Photovoltaics,Solar Cells
更新于2025-09-19 17:13:59
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17.1% Efficient Singlea??Junction Organic Solar Cells Enabled by na??Type Doping of the Bulka??Heterojunction
摘要： Molecular doping is often used in organic semiconductors to tune their (opto)electronic properties. Despite its versatility, however, its application in organic photovoltaics (OPVs) remains limited and restricted to p-type dopants. In an effort to control the charge transport within the bulk-heterojunction (BHJ) of OPVs, the n-type dopant benzyl viologen (BV) is incorporated in a BHJ composed of the donor polymer PM6 and the small-molecule acceptor IT-4F. The power conversion efficiency (PCE) of the cells is found to increase from 13.2% to 14.4% upon addition of 0.004 wt% BV. Analysis of the photoactive materials and devices reveals that BV acts simultaneously as n-type dopant and microstructure modifier for the BHJ. Under optimal BV concentrations, these synergistic effects result in balanced hole and electron mobilities, higher absorption coefficients and increased charge-carrier density within the BHJ, while significantly extending the cells’ shelf-lifetime. The n-type doping strategy is applied to five additional BHJ systems, for which similarly remarkable performance improvements are obtained. OPVs of particular interest are based on the ternary PM6:Y6:PC71BM:BV(0.004 wt%) blend for which a maximum PCE of 17.1%, is obtained. The effectiveness of the n-doping strategy highlights electron transport in NFA-based OPVs as being a key issue.
关键词： nonfullerene acceptors,molecular doping,additives,organic photovoltaics
更新于2025-09-19 17:13:59
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Achieving Organic Solar Cells with efficiency over 14% based on a non-Fullerene Acceptor incorporating the Cyclopentathiophene unit Fused backbone
摘要： The cyclopentadithiophene (CPT) unit is a classic building block for constructing organic semiconductor materials with excellent performances. In this work, we designed and synthesized a new acceptor BCPT-4F, incorporating a CPT fused central backbone. BCPT-4F shows a redshift absorption in near-infrared region compared with CPT based acceptors with unfused backbone. Importantly, the photovoltaic device based on PBDB-T:BCPT-4F gave a promising power conversion efficiency (PCE) of 12.43% with a high short circuit current density of 22.96 mA cm?2. Furtherly,based on the above binary device, the ternary device with F-Br as the third component achieved a high PCE of 14.23%, which is presently the highest efficiency for devices with CPT based photovoltaic materials.
关键词： power conversion efficiency,non-fullerene acceptor,ternary device,cyclopentadithiophene,organic photovoltaics
更新于2025-09-19 17:13:59
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Indoor Photovoltaics: Photoactive Material Selection, Greener Ink Formulations, and Slot-Die Coated Active Layers
摘要： Strong visible light absorption is essential to achieve high power conversion efficiency in indoor organic photovoltaics (iOPVs). Here, we report iOPVs that exhibit high efficiency with high voltage under excitation by low power indoor lighting. Inverted type organic photovoltaic devices with active layer blends utilizing the polymer donor PPDT2FBT paired with fullerene, perylene diimide, or ring-fused acceptors that are 6.5-9.1% efficient under 1 sun are demonstrated to reach efficiencies from 10-17% under an indoor light source. This performance transcends that of a standard silicon photovoltaic device. Moreover, we compared iOPVs with active layers both spin-cast and slot-die cast from non-halogenated solvents and demonstrate comparable performance. This work opens a path towards high efficiency iOPVs for low power electronics.
关键词： Organic Photovoltaics,Perylene Diimide Dyes,Conjugated Polymers,Roll-to-Roll Compatible Coating,Green Solvent Processing
更新于2025-09-16 10:30:52
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Preparation of Transparent Conductive Electrode via Layer-By-Layer Deposition of Silver Nanowires and Its Application in Organic Photovoltaic Device
摘要： Solution processed transparent conductive electrodes (TCEs) were fabricated via layer-by-layer (LBL) deposition of silver nanowires (AgNWs). First, the AgNWs were coated on (3-Mercaptopropyl)trimethoxysilane modified glass substrates. Then, multilayer AgNW films were obtained by using 1,3-propanedithiol as a linker via LBL deposition, which made it possible to control the optical transmittance and sheet resistance of multilayer thin films. Next, thermal annealing of AgNW films was performed in order to agent their electrical conductivity. AgNW monolayer films were characterized by UV-Vis spectrometer, field emission scanning electron microscopy, optical microscopy, atomic force microscopy and sheet resistance measurement by four-point probe method. The high performances were achieved with multilayer films, which provided sheet resistances of 9 ?/sq, 11 ?/sq with optical transmittances of 71%, 70% at 550 nm, which are comparable to commercial indium tin oxide (ITO) electrodes. Finally, an organic photovoltaic device was fabricated on the AgNW multilayer electrodes for demonstration purpose, which exhibited power conversion efficiency of 1.1%.
关键词： silver nanowires,layer by layer deposition,organic photovoltaics,transparent conductive electrode
更新于2025-09-16 10:30:52
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The green poly-lysine enantiomers as electron-extraction layers for high performance organic photovoltaics
摘要： In this study, we first revealed green materials – poly-lysines (poly-L-lysine and poly-L-lysine blend poly-D-lysine) – as electron-extraction layers (EELs) in organic photovoltaics (OPVs). The distinct configurations of poly-lysine enantiomers were verified by conducting zeta potential analysis, and their work function (WF)-tuning capabilities for indium tin oxide (ITO) were affirmed by ultraviolet photoelectron spectroscopy (UPS). These two poly-lysine groups, with different arrangements of the amino groups that built up different surface dipoles on the ITO substrate, altered the surface energy and WF of ITO. Poly-L-lysine optimized the WF of ITO for efficient carrier transport in the OPV device, in the electron transporting layer-free OPV devices, and we observed a high power conversion efficiency (PCE) of 10.01% in the device configuration of ITO/interlayer/BHJ/MoO3/Ag. As the first examination of poly-lysine enantiomers for OPVs, we provided the WF-tuning functions – increasing polarity as an interfacial dipole is formed at the corresponding interface, and discovered a promising interfacial material possessing high efficiency and benefitting from a long-term stability to perform in a stable PCE with about 80% of its original PCE remaining after continuous heat and light treatment for 400 hours.
关键词： interfacial dipole,organic photovoltaics,electron-extraction layers,poly-lysine,work function tuning
更新于2025-09-16 10:30:52
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A Projective Method for the Calculation of Excited State Electronic Coupling: Isolating Charge Transfer/Recombination Processes in Organic Photovoltaics
摘要： Electronic coupling between excited states is a vital parameter required in order to describe the ultrafast energy and charge transfer processes that occur in photo-responsive organic materials. In such systems short-range Coulombic, exchange, overlap, and configuration interaction effects must all be accounted for. Although a number of methods are available, the evaluation of the coupling between arbitrary excited states remains challenging. In this contribution, a flexible and scalable method for the calculation of short-range electronic coupling between excited states is developed. Excitation- or charge-localized states are projected onto the adiabatic states of a dimeric molecular system using an efficient wavefunction overlap algorithm. In addition to correctly treating Coulombic, exchange and overlap interactions, the inclusion of multistate interactions is inherent in the procedure. The method is then used to disentangle excitation energy transfer, charge-transfer, and charge recombination processes in donor acceptor systems relevant to organic photovoltaics, with a view towards the development of material design principles. Calculations were performed within single-excitation frameworks, but the scheme has the potential to be extended to multireference/higher-order excitation quantum-chemical methods.
关键词： excitation energy transfer,excited states,electronic coupling,charge transfer,organic photovoltaics
更新于2025-09-16 10:30:52
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How Does Polymorphism Affect the Interfacial Charge-Transfer States in Organic Photovoltaics?
摘要： The bulk heterojunction in organic photovoltaic (OPV) devices is a mixture of polymer (electron donor) and an electron acceptor material (typically functionalized fullerenes), and it is crucial for the device operation, as this is where excitons are split into electrons and holes to produce current. Non-fullerene acceptors (NFAs) are promising new materials for improving the device efficiency, and their solid-state arrangement with respect to the electron donor polymer is critical for the charge mobility and the performance of OPV devices. Although there have been numerous studies on NFAs, most of the current understanding comes from empirical considerations, with little atomistic-level interpretation of why and how the packing influences the charge transport properties of these materials. In this work we describe large-scale (with up to 3462 atoms) DFT simulations for ground and excited states on a number of polymer-NFA interfaces of realistic size, whose NFA domains consist of polymorphs of the same materials. Hence, we bridged the gap between experimental evidence and the intuitive expectation on the importance of intermolecular π-π stacking interactions in the NFA phase. We show that low connectivity leads to highly localized excitons, whereas in phases with a higher connectivity excitons are able to delocalize over multiple directions. Remarkably, excitons with a three-dimensional delocalization were also observed, leading to isotropic mobilities, similarly to fullerenes. Furthermore, a lower charge-transfer exciton binding energy and a lower energy loss between the lowest excitation of the polymer and the first charge-transfer state in the interface were both observed in systems characterized by a highly interconnected NFA phase. This suggests a higher probability of exciton splitting for these interfaces, which could potentially lead to higher device efficiencies.
关键词： organic photovoltaics,non-fullerene acceptors,DFT simulations,polymorphism,charge-transfer states
更新于2025-09-16 10:30:52
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Ternary small molecules organic photovoltaics exhibiting 12.84% efficiency
摘要： Small molecules organic photovoltaics (SMPVs) were prepared with DR3TSBDT as donor, narrow band gap material Y6 and broad band gap material PC71BM as acceptor. The Y6 based binary SMPVs exhibits a power conversion efficiency (PCE) of 10.53%, with short-circuit density (JSC) of 21.67 mA cm-2, open circuit voltage (VOC) of 0.879 V and fill factor (FF) of 55.21%. A 12.84% PCE is achieved from the optimized ternary SMPVs with 40 wt% PC71BM in acceptors, which is attributed to the enhanced JSC of 22.19 mA cm-2 and FF of 67.27% resulting from the well-optimized phase separation with PC71BM as morphology regulator. Hollow spherical structure of PC71BM with high electron mobility may connect Y6 molecules to form the more continuous electron transport channels in ternary active layers. Meanwhile, DR3TSBDT molecular arrangement can be markedly adjusted by incorporating PC71BM to form 3D texture structure. The well-optimized phase separation degree and molecular arrangement in ternary active layers can well support the enhanced FFs of ternary SMPVs compared with that of binary SMPVs. Over 21% PCE improvement is achieved by employing ternary strategy with 40 wt% PC71BM in acceptors, the 12.84% PCE should be among the highest values of SMPVs.
关键词： Small molecules organic photovoltaics,Ternary strategy,Morphology regulator,Power conversion efficiency
更新于2025-09-16 10:30:52