Studies On Perovskite Solar Cells Based On TiO₂ Nanoarrays And Their Properties

Perovskite solar cells（PSCs）have grown rapidly over the past decade,reaching an energy conversion efficiency（PCE）of 25.7 %.Benefits of this include band-gap adjustment of the perovskite material,high extinction coefficient,low exciton coupling energy and simple manufacturing process.The commercialization of PSCs presents many challenges,including high efficiency,large area,and device stability.In this paper,from the viewpoint of improving the photoelectric conversion efficiency and stability of PSCs,we propose a TiO₂ method to induce the deposition of PbI₂ and stabilize the α-FAPbI₃ phase.After investigating the role of NA transport layer for the first time,we fabricated TiO₂ NA/SnO₂ dual electronic transport layer by modification of SnCl₄,and improved device performance.They then grew a 2D layer in the original position of the perovskite surface to improve the photoelectric performance and stability of PSCs fabricated under air conditions.1.The effect of TiO₂ NA electron transport layer on guiding the deposition of PbI₂ and the stabilization of α-FAPbI₃ was studied.Nanorods with length of 0 nm,200 nm and 400 nm were prepared,characterized and assembled into batteries.The device based on 200 nm TiO₂ NA has the best performance,and the efficiency can reach 20.9 %.PEAI was used to passivate surface defects of perovskite to further improve device performance.The PCE of the optimized device can reach 21.89 % with weak current hysteresis.In addition,our equipment can maintain an initial efficiency of approximately 94 % at room temperature and dark for 800 hours in an air environment with a relative humidity of 20-30 %,demonstrating excellent equipment stability.2.SnCl₄ was used to modify TiO₂ NA to prepare TiO₂ NA+SnO₂ double electron transport layer,which increased the opening voltage of the device and improved the device performance.By comparing SnO₂,TiO₂ NA and TiO₂ NA+SnO₂ substrates,TiO₂ NA+SnO₂ double electron transport layer shows faster electron extraction and transport efficiency and better photoelectric performance compared with other substrates.TiO₂ NA was modified with 0.01 M,0.03 M and 0.05 M SnCl₄,which were characterized and assembled into batteries.It was concluded that the0.03 M SnCl₄ modification had the best photoelectric performance,and the efficiency of the assembled HTL-free carbon electrode device could reach 16.51 %.3.The stability and efficiency of PSCs were improved by in-situ growth of 2D PEA2 PbI₄coating on the surface of 3D perovskite film.This 2D perovskite film can reduce surface defect state density,improve carrier mobility,accelerate internal charge transfer,and inhibit nonradiative recombination losses,thus enhancing PCE.2D/3D perovskite champion devices achieve 17.95 % PCE and weak hysteresis.The device maintains an initial efficiency of about90 % for 800 hours at room temperature,dark and air environments with 20-30 % relative humidity,demonstrating excellent equipment stability.In addition,2D/3D+ perovskite solar cells using the improved annealing method reduced the PCE to 17.45 %,but improved stability,with the device maintaining an initial efficiency of about 95 % at room temperature,darkness and 20-30 % relative humidity in an air environment up to 800 hours.After continuous heating at 70 ℃ in the air for 10 hours,it can still maintain 90 % efficiency.