Fabrication And Properties Of Organolead Halide Perovskite Heterojunction Photodetectors

Organic-inorganic hybrid perovskite materials have a series of advantages such as large optical absorption coefficient,direct band gap adjustment,high carrier mobility and long carrier diffusion length,which is beneficial to realize photoelectric conversion in materials,and is widely used in solar thin film batteries and luminescence.In the fields of diode and photodetection.This research intends to work on the preparation and performance improvement of organic lead halide perovskite photodetectors.In this paper,a simple two-step method is used to prepare the FAPb I₃/MAPbBr₃heterojunction photodetector based on MAPbBr₃ single crystal.First,the physical and optical properties of the heterojunction are studied by means of ultraviolet absorption,band gap calculation and carrier dynamics analysis.Compared with the light absorption of MAPbBr₃ single crystal in the green wavelength band,FAPb I₃ have had a broad spectrum absorption from visible light to near infrared.This subject research has independently built a photoelectric test system using the existing conditions of the laboratory.In addition to the process and production of the device,the test system that accurately has obtained the corresponding performance parameters which also particularly important.Through the understanding of the photodetector structure and performance indicators,the instrument selection and use of the photodetector performance test system,the arrangement of the optical path and the circuit are completed,so that the built system has realized the volt-ampere characteristics of the perovskite heterojunction photodetector.key parameters such as light responsivity,detection rate,external quantum efficiency,response time and stability have been researched.The work experiment has compared the spectral responsivity of pure MAPbBr₃ single rystal and heterojunction,which is different from the only green light detection of pure MAPbBr₃ photodetector.Heterojunction photodetector exhibits rare dual narrowband photoelectricity of green and red light.Due to the difference in the depth of light excitation penetrating the crystal itself,as well as the difference in exciton lifetime and mobility,thus the two narrow-band peaks correspond to the exciton light absorption at the band edges of MAPbBr₃ and FAPb I₃,respectively.Due to the existence of the built-in electric field in the heterojunction,the photodetector has self-powered characteristics,achieving a detectivity of 5.38×10¹² Jones for red light at 0 V,and the fast response time is 6.6×10^-2 s.