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Unusual pressure-induced electronic structure evolution in organometal halide perovskite predicted from first-principles
摘要： Pressure has been demonstrated to be an effective parameter to alter the atomic and electronic structures of materials. By using the first-principles calculations based on density functional theory (DFT), we systematically investigated the changes in the atomic and electronic structures of the cubic MAPbI3 phase under pressures. It is found that the band gap of the compressed cubic MAPbI3 structure exhibits a remarkable redshift to 1.114/1.380 eV in DFT/HSE-SOC calculation under a mild pressure of 2.772 GPa, and subsequently shows a widening at higher pressures until ~20 GPa. As the pressure further increases, the band gap closes at ~80 GPa. Detailed structural and electronic characteristic analyses indicate that the band gap of the cubic MAPbI3 structure is determined by two competing effects: the lattice contraction decreases its band gap while the PbI6 octahedral tilting increases it. Given that, pressure can be a powerful tool to help understanding the optoelectronic properties of perovskite materials.
关键词： Density functional theory,Pressure,Organometal halide perovskite,Electronic structure
更新于2025-09-23 15:23:52
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Scalable Graphene-on-Organometal Halide Perovskite Heterostructure Fabricated by Dry Transfer
摘要： Graphene, a single layer conductor, can be combined with other functional materials for building efficient optoelectronic devices. However, transferring large-area graphene onto another material often involves dipping the material into water and other solvents. This process is incompatible with water-sensitive materials such as organometal halide perovskites. Here, a dry method is used and succeeded, for the first time, in stacking centimeter-sized graphene directly onto methylammonium lead iodide thin films without exposing the perovskite film to any liquid. Photoemission spectroscopy and nanosecond time-resolved photoelectrical measurement show that the graphene/perovskite interface does not contain significant amount of contaminants and sustain efficient interfacial electron transfer. The use of this method in fabricating graphene-on-perovskite photodetectors is further demonstrated. Besides a better photoresponsivity compared to detectors fabricated by the conventional perovskite-on-graphene structure, this dry transfer method provides a scalable pathway to incorporate graphene in multilayer devices based on water-sensitive materials.
关键词： photodetectors,interfaces,organometal halide perovskite,graphene,charge transfer
更新于2025-09-10 09:29:36