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Rooma??Temperature Partial Conversion of ?±a??FAPbI <sub/>3</sub> Perovskite Phase via PbI <sub/>2</sub> Solvation Enables Higha??Performance Solar Cells
摘要： The two-step conversion process consisting of metal halide deposition followed by conversion to hybrid perovskite has been successfully applied toward producing high-quality solar cells of the archetypal MAPbI3 hybrid perovskite, but the conversion of other halide perovskites, such as the lower bandgap FAPbI3, is more challenging and tends to be hampered by the formation of hexagonal nonperovskite polymorph of FAPbI3, requiring Cs addition and/or extensive thermal annealing. Here, an efficient room-temperature conversion route of PbI2 into the α-FAPbI3 perovskite phase without the use of cesium is demonstrated. Using in situ grazing incidence wide-angle X-ray scattering (GIWAXS) and quartz crystal microbalance with dissipation (QCM-D), the conversion behaviors of the PbI2 precursor from its different states are compared. α-FAPbI3 forms spontaneously and efficiently at room temperature from P2 (ordered solvated polymorphs with DMF) without hexagonal phase formation and leads to complete conversion after thermal annealing. The average power conversion efficiency (PCE) of the fabricated solar cells is greatly improved from 16.0(±0.32)% (conversion from annealed PbI2) to 17.23(±0.28)% (from solvated PbI2) with a champion device PCE > 18% due to reduction of carrier recombination rate. This work provides new design rules toward the room-temperature phase transformation and processing of hybrid perovskite films based on FA+ cation without the need for Cs+ or mixed halide formulation.
关键词： FAPbI3,two-step conversion,high performance,hybrid perovskite solar cells,quartz-crystal microbalance,in situ grazing incidence wide angle x-ray scattering
更新于2025-09-16 10:30:52
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Markedly different molecular formation in DPP-based small-molecule solar cells probed by grazing-incidence wide-angle X-ray scattering
摘要： This study comprehensively explores the nanostructural properties of two diketopyrrolo[3,4-c]pyrrole-1,4-dione (DPP)-based small molecules with different alkyl side groups and their blends with the fullerene derivative PC71BM, using grazing-incidence wide-angle X-ray scattering synchrotron techniques. Preferentially relative face-on orientation within the larger and more ordered stacking phase of SM1 with its shorter side group (ethylhexyl) was observed in the majority of both pristine and blend thin films, whereas SM2 crystals showed strictly perpendicular orientation. These contrasting crystalline characteristics led to significant differences in the results, from which crystalline structure–performance property correlations are proposed. Thus, the results not only demonstrate important scientific insights into the relationship between molecular structure and crystalline formation but also provide molecular design directions that will facilitate further improvement to the morphology and performance of DPP-based small-molecule solar cells.
关键词： small-molecule donors,diketopyrrolopyrrole,grazing-incidence wide-angle X-ray scattering,molecular packing structure,small-molecule solar cells
更新于2025-09-11 14:15:04
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Highly Efficient Indoor Organic Solar Cells by Voltage Losses Minimization through Fine-tuning of Polymer Structures
摘要： Herein we report a detailed study on the optoelectronic properties, photovoltaic performance, structural conformation, morphology variation, charge carrier mobility and recombination dynamics in bulk heterojunction (BHJ) solar cells comprising of a series of donor-acceptor (D-A) conjugated polymers as electron donors based on benzodithiophene (BDT) and 5,8-bis(5-bromothiophen-2-yl)-6,7-difluoro-2,3-bis(3-(octyloxy)phenyl)quinoxaline as a function of the BDT’s thienyl substitution (alkyl (WF3), alkylthio (WF3S) and fluoro (WF3F)). It is manifested the synergistic positive effects of the fluorine substituents on the minimization of the bimolecular recombination losses, the reduction of the series resistances (RS), the increment of the shunt resistances (RSh), the suppression of the trap-assisted recombination losses, the balanced charge transport, the finer nanoscale morphology and the deeper highest occupied molecular orbital (EHOMO) versus the alkyl- and alkylthio- substituents. According to these findings, WF3F:[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) based-organic photovoltaic (OPV) device is a scarce example that feature a high power conversion efficiency (PCE) of 17.34% under 500 lx indoor LED light with a high open-circuit voltage (VOC) of 0.69 V, due to the suppression of the voltage losses and a PCE of 9.44% at 1-sun (100 mW/cm2) conditions, simultaneously.
关键词： Series and Shunt resistances,Coherence length,Conjugated polymers,Wide-angle X-ray scattering,Organic photovoltaic devices,Recombination losses,Indoor lighting conditions
更新于2025-09-11 14:15:04