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Single-Junction Organic Photovoltaic Cells with Approaching 18% Efficiency
摘要： Optimizing the molecular structures of organic photovoltaic (OPV) materials is one of the most effective methods to boost power conversion efficiencies (PCEs). For an excellent molecular system with a certain conjugated skeleton, fine tuning the alky chains is of considerable significance to fully explore its photovoltaic potential. In this work, the optimization of alkyl chains is performed on a chlorinated nonfullerene acceptor (NFA) named BTP-4Cl-BO (a Y6 derivative) and very impressive photovoltaic parameters in OPV cells are obtained. To get more ordered intermolecular packing, the n-undecyl is shortened at the edge of BTP-eC11 to n-nonyl and n-heptyl. As a result, the NFAs of BTP-eC9 and BTP-eC7 are synthesized. The BTP-eC7 shows relatively poor solubility and thus limits its application in device fabrication. Fortunately, the BTP-eC9 possesses good solubility and, at the same time, enhanced electron transport property than BTP-eC11. Significantly, due to the simultaneously enhanced short-circuit current density and fill factor, the BTP-eC9-based single-junction OPV cells record a maximum PCE of 17.8% and get a certified value of 17.3%. These results demonstrate that minimizing the alkyl chains to get suitable solubility and enhanced intermolecular packing has a great potential in further improving its photovoltaic performance.
关键词： nonfullerene acceptors,organic photovoltaic cells,molecular modification,power conversion efficiency
更新于2025-09-23 15:21:01
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A focus on charge carrier recombination and energy conversion efficiency in nanohybrid photovoltaics
摘要： We investigated the effect of multiwall carbon nanotubes grafted with poly(3-dodecylthiophene) (CNT-graft-PDDT) on the performance of poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester photovoltaic cells. It is demonstrated that the presence of small amounts of these modified CNTs improves the structural organization of the films as evidenced by the grazing incidence wide-angle X-ray scattering studies. The ultraviolet–visible (UV–Vis) spectroscopy revealed that the incorporation of CNT-graft-PDDT changes the absorption intensity and induces a redshift to characteristic peaks. CNT hybrid features have appeared on the surface morphology as verified by atomic force microscopic images. The concentration of additive was optimized at 0.5 wt% to obtain the highest efficiency. Doping with this concentration of CNT-graft-PDDT led to 380% power conversion efficiency improvement by enhancement of short-circuit current density (Jsc) from 5.12 to 11.98 mA/cm2, open-circuit voltage (Voc) from 0.6 to 0.66 V, and fill factor from 0.41 to 0.62 in comparison with a reference cell. The photophysics of hybrid systems were also studied by means of the electrochemical impedance spectroscopy as well as Voc and Jsc dependent on the light intensity.
关键词： Organic photovoltaic cells,Charge carrier recombination,Energy conversion,CNT-graft-PDDT
更新于2025-09-23 15:21:01
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Role of Morphology of Surfactant-Free Nanoparticles in Organic Photovoltaics
摘要： Nanoparticulate (NP) ?lms and organic photovoltaic devices have been fabricated from poly(3-hexylthiophene):phenyl C61 butyric acid methyl ester (P3HT:PC61BM) NP aqueous dispersions prepared by the precipitation method. The NP inks were stable for more than 4 days, and nanoparticle organic photovoltaic (NP-OPV) devices with ef?ciency (g) of 1% were fabricated. Detailed analysis of the morphology and performance of the precipitated NP-OPV devices indicated that an optimal blend is responsible for the photocurrent and ef?ciency observed. These results were con?rmed by grazing-incidence x-ray diffraction (GIXRD) analysis, which revealed that the precipitated NPs were resistant to thermal phase segregation, allowing thermal conditioning of the NP ?lms. These results show that precipitated NPs provide a pathway to thermally stable NP-OPV devices with higher photocurrents and ef?ciencies, approaching those of optimal bulk heterojunction (BHJ) OPV devices.
关键词： ink stability,Organic photovoltaic cells (OPV),nanoparticle (NP),nanoparticle morphology,precipitation,surfactant-free
更新于2025-09-23 15:21:01
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Tuning the hybridization of local exciton and chargea??transfer states in highly efficient organic photovoltaic cells
摘要： Decreasing the energy loss is one of the most feasible ways to improve the efficiencies of organic photovoltaic (OPV) cells. Recent studies have suggested that non-radiative energy loss (ΔEnr) is the dominant factor that hinders further improvements in state-of-the-art OPV cells. However, there is no rational molecular design strategy for OPV materials with suppressed ΔEnr. In this work, taking molecular surface electrostatic potential (ESP) as a quantitative parameter, we establish a general relationship between chemical structure and intermolecular interactions. The results reveal that increasing the ESP difference between donor and acceptor will enhance the intermolecular interaction. In the OPV cells, the enhanced intermolecular interaction will increase the charge transfer (CT) state ratio in its hybridization with local exciton to facilitate the charge generation but simultaneously result in a larger ΔEnr. These results suggest that finely tuning the ESP of OPV materials is a feasible method to further improve the efficiencies of OPV cells.
关键词： hybridization,charge transfer state,intermolecular interaction,organic photovoltaic cells,non-radiative energy loss
更新于2025-09-23 15:19:57
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On the use of multiple stacked active layers in organic photovoltaic cells
摘要： In the field of organic photovoltaic cells (OPVs), ternary planar heterojunction allows widening absorption range. Optimization of the energy levels at the organic interfaces is the first task to achieve in order to obtain OPVs with high efficiency. In ternary OPVs, carrier mobility, charge transfer and presence of energy transfer are determinant. Here, we compare the performances of different, binary (electron donor/fullerene) and ternary (electron donor/ambipolar material/fullerene) combinations of small organic molecules in planar heterojunction (PHJ) cells. We chose the different ED molecules in order to investigate the different possible band scheme alignments. The study shows that if the open circuit voltage (Voc) is limited by the energy levels of the outer layers, i.e. the difference between the lowest unoccupied molecular orbital (LUMO) of the electron acceptor and the highest occupied molecular orbital (HOMO) of the outer electron donor layer, the energy loss can be smaller than 0.2 eV. If efficient ternary OPVs need global energy offset higher than the exciton energy to separate the charges of the exciton, the distribution of this offset between DLUMO and DHOMO is not critical. The mobility value of the carriers in the intercalated layer is determinant in obtaining performance of OPVs. Overlap between the photoluminescence of ED and the optical absorption of EDA is primordial for good energy transfer. The highest OPV efficiency improvement is obtained with organic materials such as ED and EDA that have the same HOMO and similar hole mobility which give homogeneous thin layers.
关键词： organic photovoltaic cells,energy levels,energy transfer,carrier mobility,charge transfer,ternary planar heterojunction
更新于2025-09-23 15:19:57
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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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Thin film deposition method for ZnO nanosheets using low-temperature microwave-excited atmospheric pressure plasma jet
摘要： Electronic devices such as solar cells and thin-film transistors can be fabricated using thin-film deposition. Low-cost, low-temperature and high-speed deposition methods are required to ensure that the production of devices using thin-film deposition is affordable. Herein, we report the development of a low-cost and simple thin-film deposition method using microwave-excited atmospheric pressure plasma jet (MWAPPJ). MWAPPJ produces a low-temperature (several hundred degrees) plasma under atmospheric conditions, does not require expensive vacuum equipment, and it enables high-speed deposition of thin-films. Zinc acetylacetonate sol-gel precursors that were adhered to stainless steel mesh targets were irradiated by MWAPPJ with oxygen, which resulted in zinc oxide (ZnO) nanosheet thin-films with diameters of 100–200 nm on silicon substrates. We used 50-nm-thick ZnO thin-films that were processed using MWAPPJ as the electron collection layer in organic photovoltaic (OPV) cells. This work represents an important contribution to the design and production of low-cost OPV solar cells.
关键词： Thin-films,Electron Collection layer,Nanostructured Zinc Oxide,Organic Photovoltaic Cells.,Microwave-excited Atmospheric Pressure Plasma Jet
更新于2025-09-19 17:15:36
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Metala??organic framework nanosheets for enhanced performance of organic photovoltaic cells
摘要： Metal-organic nanosheets (MONs) are an emerging class of two-dimensional materials whose diverse and readily tunable structures make them ideal for use in optoelectronic applications. Here, liquid exfoliation is used to synthesize ultrathin zinc-porphyrin based MONs with electronic and optical properties ideally suited for incorporation into a polythiophene-fullerene (P3HT-PCBM) organic solar cell. Remarkably, the addition of MONs to the photoactive layer of a photovoltaic device results in a power conversion efficiency of 5.2%, almost twice that for reference devices without nanosheets with a simultaneous improvement of Jsc, Voc and FF. Our analysis indicates that the complimentary electronic, optical and structural properties of the MONs allows them to act as a surface to template the crystallization of P3HT leading to a doubling of the absorbance, a tenfold increase in hole mobility and reduced grain size. These results demonstrate the potential of MONs as a tunable class of two-dimensional materials for enhancing the performance of a broad range of organic solar cells and other electronic devices.
关键词： Metal-organic nanosheets,organic photovoltaic cells,power conversion efficiency,liquid exfoliation,zinc-porphyrin
更新于2025-09-19 17:13:59
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Nonfullerene organic photovoltaic cells exhibiting 13.76% efficiency by employing upside‐down solvent vapor annealing
摘要： Organic photovoltaic cells (OPVs) are fabricated with a polymer donor PM7 and a nonfullerene acceptor IT‐4Cl; the morphology of active layers is optimized by employing upside‐down solvent vapor annealing (UD‐SVA) method with different annealing solvents. The OPVs with CS2 as annealing solvent exhibit optimized power conversion efficiency (PCE) of 13.76%, with simultaneously increased short‐circuit current density (JSC) of 20.53 mA cm?2 and fill factor (FF) of 77.05%. More than 15% PCE improvement can be achieved by employing CS2 UD‐SVA treatment, which should be attributed to slightly enhanced photon harvesting, efficient exciton separation, charge transport, and collection, resulting from the well‐developed morphology of active layer. Moreover, the PM7:IT‐4Cl–based OPVs with CS2 as annealing solvent still can maintain PCE more than 13% in a wide treatment time range from 20 to 90 seconds. This work demonstrated that UD‐SVA has great potential in improving the performance of nonfullerene OPVs.
关键词： phase separation,organic photovoltaic cells,solvent vapor annealing,nonfullerene
更新于2025-09-19 17:13:59
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Tuning the hybridization of local exciton and chargea??transfer states in highly efficient organic photovoltaic cells
摘要： Decreasing the energy loss is one of the most feasible ways to improve the efficiencies of organic photovoltaic (OPV) cells. Recent studies have suggested that non-radiative energy loss ( ) is the dominant factor that hinders further improvements in state-of-the-art OPV cells. However, there is no rational molecular design strategy for OPV materials with suppressed . In this work, taking molecular surface electrostatic potential (ESP) as a quantitative parameter, we establish a general relationship between chemical structure and intermolecular interactions. The results reveal that increasing the ESP difference between donor and acceptor will enhance the intermolecular interaction. In the OPV cells, the enhanced intermolecular interaction will increase the charge transfer (CT) state ratio in its hybridization with local exciton to facilitate the charge generation but simultaneously result in a larger . These results suggest that finely tuning the ESP of OPV materials is a feasible method to further improve the efficiencies of OPV cells.
关键词： hybridization,charge transfer state,intermolecular interaction,organic photovoltaic cells,non-radiative energy loss
更新于2025-09-19 17:13:59