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Hydrogen Plasma–Treated MoSe2 Nanosheets Enhance the Efficiency and Stability of Organic Photovoltaics
摘要： In this paper we report the effect on the power conversion efficiency (PCE) and stability of photovoltaic devices after incorporating hydrogenated two-dimensional (2D) MoSe2 nanosheets into the active layer of bulk heterojunction (BHJ) organic photovoltaics (OPV). The surface properties of 2D MoSe2 nanosheets largely affect their dispersion in the active layer blend and, thus, influence the carrier mobility, PCE, and stability of corresponding devices. We treated MoSe2 nanosheets with hydrogen plasma and investigated their influence on the polymer packing and fullerene domain size of the active layer. For the optimized devices incorporating 37.5 wt% of untreated MoSe2, we obtained a champion PCE of 9.82%, compared with the champion reference PCE of approximately 9%. After incorporating the hydrogen plasma–treated MoSe2 nanosheets, we achieved a champion PCE of 10.44%—a relative increase of 16% over that of the reference device prepared without MoSe2 nanosheets. This PCE is the one of the highest ever reported for OPVs incorporating 2D materials. We attribute this large enhancement to the enhanced exciton generation and dissociation at the MoSe2–fullerene interface and, consequently, the balanced charge carrier mobility. The device incorporating the MoSe2 nanosheets maintained 70% of its initial PCE after heat-treatment at 100 °C for 1 h; in contrast, the PCE of the reference device decreased to 60% of its initial value—a relative increase in stability of 17% after incorporating these nanosheets. We also incorporated MoSe2 nanosheets (both with and without treatment) into a polymer donor (PBDTTBO)/small molecule (IT-4F) acceptor system. The champion PCEs reached 7.85 and 8.13% for the devices incorporating the MoSe2 nanosheets with and without plasma treatment, respectively—relative increases of 8 and 12%, respectively, over that of the reference. These results should encourage a push toward the implementation of transition metal dichalcogenides to enhance the performances of BHJ OPVs.
关键词： hydrogen plasma treatment,organic photovoltaics,stability,MoSe2 nanosheets,power conversion efficiency
更新于2025-09-11 14:15:04
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Synthesis of Alkoxyacene‐Based Random Copolymers and Binary Solvent Additive for High Efficiency Organic Photovoltaics
摘要： The synthesis of three random copolymers—BD2FON-OB30, BD2FON-OB50, and BD2FON-OB70—comprised of different molar ratios of alkoxyphenylene and alkoxynaphthalene is reported by adjusting the ratio of these units for optimized energy levels. When organic photovoltaics are fabricated using these polymers as the electron donor, introduction of the binary solvent additive dramatically enhances power conversion efficiency (PCE) up to 7%, compared to those of the devices without additive (≈2% of PCEmax) and with single additive (≈3% of PCEmax). (without additive: 1–2% and with single additive: 0–3%). These improvements result from minimized bimolecular recombination and balanced electron/hole mobility ratio by optimized bicontinuous D:A morphology in the active layer. Thus, the strategy shows the efficient enhancement of device efficiency by control the morphology using binary solvent additives in the bulk heterojunction film consisting of polymer and fullerene.
关键词： binary solvent additives,organic photovoltaics,random copolymers
更新于2025-09-11 14:15:04
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Watching Space Charge Build up in an Organic Solar Cell
摘要： A method is presented to spatially resolve the space charge region in organic photovoltaics (OPVs) by measuring white-light bias EQE and optical modeling. The method is demonstrated for a model polymer/fullerene blend with imbalanced carrier mobilities. Furthermore, numerical and analytical means are derived to discuss the general thickness limits for OPVs with imbalanced transport.
关键词： thick films,imbalanced charge transport,quantum efficiency,Organic photovoltaics,space charge
更新于2025-09-11 14:15:04
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Designing High Performance Nonfullerene Electron Acceptors with Rylene Imides for Efficient Organic Photovoltaics
摘要： Improving carrier mobility, redox stability, blend morphology, and photovoltaic performance while elucidating structure-property relationships remain important design goals for nonfullerene electron acceptors (NFAs) for organic solar cells. Although numerous NFAs have been created from rylene diimide electron-deficient building blocks, they have showed far inferior photovoltaic properties compared to benchmark fused-ring electron acceptors (FREAs) such as ITIC. Herein we show that new bis(naphthalene-imide)arylenelidenes (BNIAs), incorporating rylene-imide end-capping groups via methine bridges in donor-acceptor architectures, are endowed with enhanced electrochemical redox stability, high carrier mobilities, and high photovoltaic performance. Pairing of those BNIAs that are also FREAs, NIDT and NIBT, respectively with donor polymer PBDB-T produced 10.0-10.8% efficient photovoltaic devices, which are comparable to benchmark ITIC devices. Blends of FREAs NIDT and NIBT and those of non-FREA NITV were found to have similar electron mobility, demonstrating that the much higher photovoltaic efficiency of NIDT and NIBT devices does not originate from enhanced charge transport but from differences in blend morphology and blend photophysics. The results demonstrate that incorporating rylene imides into molecular architectures through methine-bridged donor-acceptor coupling motif is a promising design strategy towards more efficient and electrochemically rugged materials for organic solar cells.
关键词： organic photovoltaics,carrier mobility,redox stability,photovoltaic performance,nonfullerene electron acceptors,rylene imides
更新于2025-09-11 14:15:04
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High-yield production of stable antimonene quantum sheets for highly efficient organic photovoltaics
摘要： High-performance organic photovoltaics (OPVs) are of great scientific and technological importance due to their potential large-scale industrial applications. Introducing semiconductor quantum dots has been proven to be an effective way to improve the power conversion efficiency (PCE) of OPVs. In this paper, we report a novel approach to fabricate atomically thin antimonene quantum sheets (AMQSs) possessing a uniform size (～2.2 nm) via imidazolium ionic liquid-assisted exfoliation. In this method, the yield of AMQSs (1.1 mg mL?1) has been increased by nearly two orders of magnitude compared with that of previously reported methods. Furthermore, upon adding AMQSs into the light absorber in OPVs, the optimal device with 1.0 mg mL?1 AMQSs shows the highest PCE of 9.75%, resulting in over 25% enhancement in PCE compared to that of the reference device. It also leads to a noticeable enhancement in the short-circuit current density (Jsc) of 16.7% and the fill factor (FF) of 8.4%. The increased PCE is mainly due to the two-dimensional electronic structure of AMQSs that can enhance the light absorption, assist exciton dissociation and reduce charge recombination of OPVs. This work provides a new avenue toward mass production of two-dimensional quantum sheets and points to a new strategy for highly efficient OPVs.
关键词： antimonene quantum sheets,organic photovoltaics,power conversion efficiency,ionic liquid-assisted exfoliation,two-dimensional materials
更新于2025-09-11 14:15:04
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Flexible organic photovoltaics based on water-processed silver nanowire electrodes
摘要： A key feature of organic electronic devices is their mechanical flexibility. However, the performance of flexible organic optoelectronic devices still lags behind the performance of devices on rigid substrates. This is due, in particular, to the lack of flexible transparent electrodes that simultaneously offer low resistance, high transparency and a smooth surface. Here, we report flexible transparent electrodes created using water-processed silver nanowires and a polyelectrolyte. Due to ionic electrostatic charge repulsion, the nanowires form grid-like structures in a single step, leading to smooth, flexible electrodes that have a sheet resistance of around 10 Ω □?1 and a transmittance of around 92% (excluding the substrate). To illustrate the potential of the approach in organic electronics, we use the flexible electrodes to create organic photovoltaic devices. The devices are tested with different types of donors and acceptors, and exhibit performance comparable to devices based on commercial rigid electrodes. Furthermore, flexible single-junction and tandem devices achieve power conversion efficiencies of 13.1% and 16.5%, respectively.
关键词： silver nanowires,flexible electronics,transparent electrodes,organic photovoltaics
更新于2025-09-11 14:15:04
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Effect of an Al-doped ZnO electron transport layer on the efficiency of inverted bulk heterojunction solar cells
摘要： Doping is a widely-implemented strategy for enhancing the inherent electrical properties of metal oxide charge transport layers in photovoltaic devices because higher conductivity of electron transport layer (ETL) can increment the photocurrent by reducing the series resistance. To improve the conductivity of ETL, in this study we doped the ZnO layer with aluminum (Al), then investigated the influence of AZO on the performance of inverted bulk heterojunction (BHJ) polymer solar cells based on poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl]-[3-fluoro-2[(2-ethylhexyl)-carbonyl]-thieno-[3,4-b]thiophenediyl ]] (PTB7):[6,6]-phenyl C71 butyric acid methyl-ester (PC71BM). The measured conductivity of AZO was ~10-3 S/cm, which was two orders of magnitude higher than that of intrinsic ZnO (~10-5 S/cm). By decreasing the series resistance (Rs) in a device with an AZO layer, the short circuit current (Jsc) increased significantly from 15.663 mA/cm2 to 17.040 mA/cm2. As a result, the device with AZO exhibited an enhanced power conversion efficiency (PCE) of 8.984%.
关键词： ZnO,organic photovoltaics,conductivity,doping,electron transport layer
更新于2025-09-11 14:15:04
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Study of Photovoltaic Devices with Hybrid Active Layer
摘要： The aim of this work is to present the influences of composition of the material and manufacturing technology conditions of the organic photovoltaics devices (OPv) with the organic and hybrid bulk heterojunction on the active layers properties and cells performance. The layers were produced by using small molecular compounds: the metal-phthalocyanine (MePc) and perylene derivatives (PTCDA) and the titanium dioxide (TiO2) nanoparticles. Two kinds of metal phthalocyanines (NiPc, TiOPc) were used as donor material and pperylenetetracarboxylic dianhydride (PTCDA) as an acceptor. The used manufacturing technique allowed to employ thin layers of materials in a fast deposition process. Bulk heterojunction was created by simultaneously applying the MePc:PTCDA materials during the evaporation of the components mixture. The research was based on the estimate of composition of bulk heterojunction, the examination of the surface morphology of the used layers and optical properties studies of the heterojunction and its implementation to photovoltaic architecture. The produced photovoltaic cells parameters were determined on the basis of current - voltage characteristics. The researches of structure of obtained layers were conducted by using scanning electron microscope (SEM) and transmission electron microscopy (TEM). The quantitative determination of surface topography by determining RMS and Ra coefficients were performed by atomic force microscopy (AFM). In order to determine the optical properties of the films the UV-Visible spectroscope have been utilized. Current - voltage characteristics were employed to determine the basic photovoltaic parameters using a dedicated device. The paper describes the influence of the individual components sharing the bulk heterojunction on its structure, optical properties and morphology of surface. In addition it allows for linking active layers properties with the parameters of the photovoltaic cells. The obtained results suggest the possibility of developing the utilized materials and technology in the further works on photovoltaic structures.
关键词： metal-phthalocyanine,titanium dioxide nanoparticles (TiO2),organic photovoltaics devices (OPv),perylene derivatives
更新于2025-09-11 14:15:04
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Regioregularity and Electron Deficiency Control of Unsymmetric Diketopyrrolopyrrole Copolymers for Organic Photovoltaics
摘要： Manipulating the electron deficiency and controlling the regioregularity of π-conjugated polymers are important for the fine-tuning of their electronic and electrochemical properties to make them suitable for an organic solar cell. Here, we report such a molecular design of unsymmetric diketopyrrolopyrrole (DPP) based copolymers with different aromatic side units of either thiophene (Th), pyridine (Py), or fluorobenzene (FBz). The unsymmetric electron acceptors of Th?DPP?Py and Th?DPP?FBz were polymerized with the electron donor of two-dimensional benzobisthiophene (BDT-Th), affording two regiorandom DPP copolymers. They exhibited contrasting molecular orbital levels and bulk heterojunction morphology in methanofullerene-blended films, leading to power conversion efficiencies of 3.75 and 0.18%, respectively. We further synthesized a regioregular DPP copolymer via sandwiching the centrosymmetric BDT-Th unit by two Th?DPP?Py units in an axisymmetric manner. The extensive characterization through morphology observation, X-ray diffraction, and space-charge-limited current mobilities highlight the case-dependent positive/negative effects of regioregularity and electron deficiency control.
关键词： diketopyrrolopyrrole,organic photovoltaics,electron deficiency,regioregularity,power conversion efficiency
更新于2025-09-11 14:15:04
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Non-Fullerene Small Molecule Acceptors Containing Barbituric Acid End Groups for Use in High-performance OPVs
摘要： We synthesized two new bithiophene-based small molecules, TT-BBAR, and TT-OBAR, having butyl- and octyl-substituted barbituric acid (BAR) groups, respectively, via a well-known synthetic method, the Knoevenagel condensation, in high yield. These small molecules displayed solubilities and thermal stabilities sufficient for the fabricating organic photovoltaic cells (OPVs) and were designed to have relatively low molecular orbital energy levels and act as non-fullerene acceptors (NFAs) for use in OPVs upon introduction of electron-withdrawing BAR groups at both ends. For example, the LUMO and HOMO energy levels of TT-OBAR were ?3.79 and of ?5.84 eV, respectively, clearly lower than those of a polymer donor, PTB7-Th. Importantly, the small molecules featured an energy offset with PTB7-Th sufficient for achieving exciton dissociation. The optical and electrochemical properties of TT-BBAR and TT-OBAR did not depend on the alkyl chain length. Finally, OPV devices were fabricated in an inverted structure using a solvent process. The power conversion efficiency of TT-OBAR (1.34%) was found to be slightly higher than that of TT-BBAR (1.16%). The better performance and higher short-circuit current value of TT-OBAR could be explained based on a morphological AFM study, in which TT-OBAR displayed a more homogeneous morphology with a root-mean-square value of 1.18 nm compared to the morphology of TT-BBAR (11.7 nm) induced by increased alkyl chain length.
关键词： Barbituric acid,Organic photovoltaics,Organic photovoltaic cell,Non-fullerene acceptor
更新于2025-09-10 09:29:36