Perovskite-based Thin Film Morphology Control And Detector Design

Organic-inorganic hybrid lead halide perovskite material is a new type of semiconductor material.Owing to its long carrier transmission distance,high light absorption coefficient,tunable bandwidth,large absorption range covering from ultraviolet to near-infrared and other excellent photoelectronic properties,it has become a research hotspot in the field of optoelectronic materials in recent years and shown bright application prospects in photodetection.In the application of optoelectronic devices,perovskite photodetector can be prepared with low-cost solution method.However,the thin film prepared by the solution method still faces some problems such as uneven morphology and difficulty in large-area device manufacturing.To solve these problems,this work mainly focuses on the research of perovskite film morphology control and design of film with microstructure and the preparation of perovskite photodetector.Two strategies were developed to improve the performance of the prepared photodetector,including film morphology control by adjusting solvent composition of perovskite precursor,and the design of network-structured thin film.In details:Firstly,a new method is proposed to prepare perovskite photodetector which is to combine patterned ITO electrodes on highly transparent glass substrate and one-step spin coating method without anti-solvent for perovskite thin film.By adjusting the volume ratio of the two solvents N-N dimethyl amide(DMF)and dimethyl sulfoxide(DMSO)in the precursor,the coordination interaction between the solvent and the perovskite precursor can be adjusted,thereby regulating the surface of the film morphology and photoelectronic properties of the detector.Experiment results show that the adjustment of the solvent ratio can effectively adjust the performance of the photodetector.This is mainly due to the stronger coordination ability of the mixed solvent with DMSO added to the solute,which retards the speed of perovskite crystallization,makes the film surface coverage higher and has fewer defects.The optimized photodetector has a maximum responsivity of 1.75A·W^-1,a specific detection rate of 3.54×10¹²Jones,and a detection wavelength range of 400?780 nm.In addition,the transparent structure enables light detection from the bottom side.Meanwhile,ITO electrode is easy to prepare and integrate,and the cost is lower than that of traditional vapor-deposited metal electrode.Secondly,a method for two-dimensional network-structured perovskite thin film based on self-assembled polystyrene microsphere template is proposed.By one-step spin coating method,perovskite is grown around the polystyrene microsphere template formed by self-assembly.After soaking in toluene,polystyrene can be removed.The prepared two-dimensional perovskite thin film has a neat and compact arrangement structure,which can effectively enhance the absorption of incident light,and thus improve the performance of photodetector.X-ray diffraction spectrum proves that the two-dimensional network structure does not affect the crystal structure of perovskite.