Patterned Preparation And Photodetection Properties Of MAPbBr₃ Single Crystal Perovskite Thin Films

The emergence of organic-inorganic perovskite hasprovided great flexibility for creating optoelectronic devices with unprecedented performance or unique functionality.However,theperovskite films explored so far have been difficult to be patterned toarrays owing to their poor solvent and moisture stability,whichusually lead to serious structural damage of perovskites.The successful preparation of perovskite microarrays with uniform shapeand size is more challenging.Here we report a straightforward approach to realize single-crystalline perovskite arrays through arelatively simple pattern-selective molecular epitaxial growth.This approach is applied to create diverse shaped perovskite arrays,such as hexagon,triangle,circle,square,and rectangle.A vertically aligned perovskite photodetector displays both an ultrasensitive and ultrafast photoresponse arising from the reduction in carrier diffusion paths and the high optical absorption.This work demonstrates a general approach to creating perovskite arrays with uniform shape,size,and morphology and provides a rich platform for producing high-performance photodetectors and photovoltage devices.The specific research results of this thesis are as follows:(1)The surface morphology and crystalline properties of the perovskite thin films were optimized,and the molecular-induced epitaxial growth was realized through the spatial confinement effect and the introduction of amino functional groups,and high-performance monoliths with controllable thickness,shape and size of hundreds of nanometers were successfully prepared.Crystalline perovskite thin film arrays.(2)Au/MAPb Br₃/graphene vertical heterojunction photodetector was prepared based on high-performance single-crystal perovskite thin film material,and the device achieved picowatt sensitivity and microsecond response speed.(3)The relationship between sensitivity,response speed and light intensity of Au/MAPb Br₃/graphene vertical heterojunction photodetector was systematically studied.As the incident light intensity increases from picowatts to nanowatts,the photocurrent increases by 2 orders of magnitude and the photoresponse speed increases by a factor of3.The excellent performance of single crystal perovskite thin film detectors,such as high sensitivity and high response speed,comes from the simultaneous optimization of the thickness,crystallinity and morphology of MAPb Br₃functional materials,which reduces the transmission loss of photogenerated carriers and reduces photogenerated carriers.scattering,increasing its collection efficiency.