Study On High Performance Of Perovskite Solar Cells Based On Two-step Spin Coating Method

Since an organometal halide was synthesized,perovskite solar cells(PSCs)have became a key subject in the field of photovoltaic technology,because the lead halide perovskite materials have a lot of advantages such as high carrier mobility,low exciton energy and long diffusion lengths.Perovskite layer,a critical component in the structure of PSCs,bear the burden of harvesting light as well as generating electronics and holes.Therefore,high-quality perovskite film is significantly for photovoltaic performance of PSCs.In order to enhance absorption intensity,suppress charge recombination and improve photon-to-electricity conversion efficiency(PCE)of PSCs,the excellent perovskite film should possess the characteristics of high coverage rate,continuous,dense,uniform,flat and so on.In this paper,the crystallinity and surface morphology of perovskite film as well as the PCE of PSCs were enhanced via optimizing the preparation technology,controlling crystallization process and adjusting energy band gap.The main results are listed as follows:1.Perovskite film was prepared by pre-coating CH3NH3I/isopropanol solution based on two-step spin coating method.A high-quality CH3NH3 Pb I3 film was achieved by adopting pre-coating 15 mg/mL CH3NH3I/isopropanol solution,which was demonstrated by XRD、SEM and UV-Vis.Then,we fabricated mesoporous PSCs and shown that the PCE of devices increased from 9.24% to 12.4%.2.The high boiling point solvents were introduced into CH3NH3I/isopropanol solution and n-butylalcohol can enhance the PCE of PSCs.Further research show that the crystallinity of CH3NH3 Pb I3 grain was increased,the surface morphology and light absorption of perovskite film were improved with introducing moderate n-butylalcohol.Moreover,the best PCE of 14.64% was obtained by adopting 2% n-butylalcohol.3.To improve the surface morphology and promote light absorption of perovskite film,mixed-organic-cation(MA)1-x(FA)xPb I3(x=0-1)perovskite film was prepared by introducing HC(NH2)2+(FA+)into the lattice structure CH3NH3PbI3(MAPb I3).We found that more visible light and near-infrared light was absorbed by(MA)1-x(FA)xPbI3 film,due to the FA+ can change the lattice parameter and decrease the energy band gap of perovskite material.In addition,(MA)0.875(FA)0.125PbI3 film was applied to mesoporous PSCs and achieve the PCE of 13.44% with the short-circuit photocurrent density(Jsc)of 18.63 mA/cm2.In this research,many high-quality perovskite films were prepared successfully,which provide a new idea for fabricate excellent PSCs in the aspects of depositing perovskite film,improving surface morphology and exploring new perovskite materials.