Preparation And Properties Of MAPbBr₃ Perovskite Thick Film Optoelectronic Device

In recent years,organic-inorganic hybrid halide perovskite materials have been widely used in perovskite solar cells,light-emitting diodes,and photodetectors due to their excellent physical and chemical properties.X-ray detectors are important photodetectors,and the research on MAPbBr₃-based perovskite X-ray detectors mainly focuses on single crystals.However,perovskite single crystals have many disadvantages,such as long growth cycles,difficult preparation of large areas,and difficulty in integrating with electrode arrays.In addition,the electrode materials for perovskite-based photodetectors are mostly high-cost precious metals such as gold and silver,which are expensive and generally prepared by complex processes such as high-vacuum evaporation and magnetron sputtering.In response to this situation,this paper successfully prepared structurally controllable MAPbBr₃ polycrystalline thick films by spray deposition process,and studied their phase structure and optical properties.In addition,by combining with carbon electrodes prepared by a scrape-off technique,multilayer film devices were prepared and their optoelectronic properties were tested.The specific research contents are as follows:A spray deposition process was systematically developed to prepare MAPbBr₃ perovskite polycrystalline thick films with a thickness greater than 40μm.The phase structure and surface morphology of the thick films were characterized by XRD and SEM,and the optoelectronic properties of the solar cells with MAPbBr₃ polycrystalline thick films as the absorbing layer were studied.The results showed that the perovskite layer obtained by the spray deposition process had excellent crystallinity,was closely combined with the Ti O₂ electron transport layer and carbon electrode layer,and had fewer vertical grain boundaries,which was conducive to the transport of carriers in the perovskite device.Under AM 1.5 illumination,the photovoltaic conversion efficiency of the MAPbBr₃ thick film solar cell prepared by this method exceeded 5.5%.The excellent photovoltaic performance indicated that the photogenerated holes could efficiently transport through the perovskite film with a thickness of more than 40μm,which was beneficial to the transport and collection of photogenerated carriers in the MAPbBr₃ perovskite thick film device.MAPbBr₃ thick film X-ray detectors with an active layer thickness of over 100μm were prepared and characterized for their response to X-rays of different intensities.Under X-ray irradiation,the device had a high response value without external bias voltage.With the increase of reverse bias voltage,the sensitivity of the device increased,up to a maximum of 637μC·Gy^-1·cm^-2.The photocurrent increased with increasing applied voltage.In addition,the prepared MAPbBr₃ thick film device had good repeatability and stability in air.A large area MAPbBr₃ thick film detector array（4×4 pixels）with a size of 5×5 cm² was prepared.The imaging results showed that the response values of different pixels to X-rays were uniform and the imaging was clear.On the basis of measuring the asymmetrical structure of MAPbBr₃ thick film X-ray detectors,MAPbBr₃ thick film X-ray detectors with symmetrical carbon electrode structures were successfully prepared.The detection ability of the device to X-rays was explored through a series of characterizations.The results showed that the MAPbBr₃ thick film device with symmetrical carbon electrode structure had good stability and repeatability,and the X-ray sensitivity was increased by 30 times compared with the MAPbBr₃ thick film device based on Ti O₂ substrate,reaching 18610μC·Gy^-1·cm^-2at a bias voltage of-0.9 V.Based on its low cost,simple process,good stability,and high sensitivity,MAPbBr₃ thick film X-ray detectors with symmetrical carbon electrode structures have great value in scientific research and applications.