Photovoltaic And Resistive Switching Characterisitcis Of Solution-processed NiO/CH₃NH₃PbI₃ Stack

Organic-inorganic halide perovskite is one of hybrid perovskite materials,it has been widely used in various photoelectric devices due to its easy fabrication,low cost and excellent photoelectric characteristics.Up to now,a record power conversion efficiency of 25.2%has been certified in organic-inorganic halide perovskite solar cells,showing potential candidate for conventional silicon solar cells.However,several problems such as poor air stability and heavy voltage-current hysteresis still hinder their application.However,its hysteresis is benefit for application in resistive switching device.Morover,its electronic-ionic conductivity and photosensitivity is helpful to explore new-generation photosenstive resistive switching device.On the other hand,p-type semiconductor nickel oxide（NiO）is an excellent inorganic hole transporting material with stable chemical properties,wide optical band gap,large light transmission and energy band matched with organic-inorganic halide perovskite.In this paper,we have prepared NiO/CH₃NH₃Pb I₃ stack structures by solution method,and studied their photovoltaic and resistive switching properties.Main research results are as follows:（1）We prepared the solar cells with planar inverted structure of NiO/CH₃NH₃Pb I₃/PCBM on ITO or FTO substrates by solution method.Effects of transparent electrode,spin-coating times and precursor concentration on the surface morphology and photovoltaic characteristics of cells were studied.Under optimized preparation conditions,cells obtained a power conversion efficiency of 16.69%with a high open circuit voltage of 1.04 V,which is superior to the photovoltaic properties of organic-inorganic halide perovskite solar cells prepared by similar solution method.（2）We also studied resistive switching properties of NiO/CH₃NH₃Pb I₃ stack.Effects of NiO film thickness and CH₃NH₃Pb I₃ film annealing temperature on resistive switching performance were studied.NiO/CH₃NH₃Pb I₃stack consisted by 80 nm-thick NiO film and70℃-annealed CH₃NH₃Pb I₃ film exhibits stable resistive switching properties with ultra-low switching voltage（0.2～0.5 V）:ON/OFF ratio is higher than 10³,current-voltage loops can repeat for more than 400 cycles in air ambient.Multi-level resistive switching characteristics were achieved by adjusting compliance current and illumination.Under applied electric fileld,NiO/CH₃NH₃Pb I₃ interfacial region acts as a reverse biased‘p-n heterojunction’,both‘iodine-vacancy conductive filaments’and the‘interfacial p-n junction effect’are responsible for the resistive switching properties.In this paper,devices with organic-inorganic composited stack structure of NiO/CH₃NH₃Pb I₃ were prepared by solution method,which not only exhibits good photovoltaic performance,but also shows unique resistive switching characteristics with low switching voltage.It provides a new path and reference for designing new-type inorganic-organic composite photosensitive resistive switching device.