Structure Design And Performance Investigation On High External Quantum Efficiency Photodetectors Based On Lead Methylamine Iodide

Photodetectors are a type of device that can convert incident light into electrical signal,which are widely used in many scientific fields such as aerospace,optical communications,environmental monitoring,and biological sensing.In recent years,the organic-inorganic perovskite,especially the most typical MAPb I₃,has shown excellent photoelectric properties.Its high optical absorption coefficient,high carrier mobility and long carrier diffusion length provide broad prospects for the development of high-performance photodetectors.A large number of researches have also shown that MAPb I₃photodetectors can have excellent detection capabilities.For photodetectors,the most basic performance parameter is the external quantum efficiency,and the responsivity and detectivity of the photodetector are positively correlated with it.Therefore,it is very necessary to improve the external quantum efficiency of the MAPb I₃photodetector,further optimize the device structure and obtain high-performance devices on the basis of the existing.In this paper,we took MAPb I₃and its devices as the research objects,optimized the synthesis method of MAPb I₃and the structure of the devices,and improved the external quantum efficiency of the devices while obtaining high-quality MAPb I₃films.The research contents of this paper are as follows:(1)The solution method is used to prepare MAPb I₃films.We doped an appropriate amount of methylammonium chloride into the perovskite precursor solution to improve the crystal quality and surface morphology of the perovskite film.Through the analysis of the electrical properties of the devices with or without methylammonium chloride,we found that the peak external quantum efficiency of the devices with methylammonium chloride increased from 67%to81%,the responsivity increased from 0.38 A W^-1to 0.45 A W^-1,and the detectivity increased from 7.03×10¹¹Jones to 2.71×10¹²Jones.OAfter the devices were doped with methylammonium chloride,other performance parameters were improved.(2)In order to break the limit that the external quantum efficiency is less than 100%and obtain the devices with higher responsivity and detectivity,we designed the interfaces to achieve this purpose.We use vapor-assisted and vacuum processing technology to prepare high-quality MAPb I₃films on C₆₀(A).A double C₆₀layer structure were designed to improve the external quantum efficiency of the devices and the ultimate device structure is ITO/C₆₀(A)/MAPb I₃/C₆₀(B)/Al.Benefiting from the tunneling effect between C₆₀(A)and ITO,the peak external quantum efficiency of our device is up to 140000%.A high detectivity of 1×10¹⁴Jones and a responsivity of over 600 A W^-1under a bias of-5 V were obtained.The fabricated devices manifested outstanding environmental stability with only 10%degradation of external quantum efficiency after being exposed to air for 24 hours.