| The methylammonium lead bromide-based solar cell has large voltage potential and high stability.It has received widespread attention from the academic for it is a promising candidate for the window layer of the tandem solar cells.The perovskite films prepared by vapor-assisted solution deposition method are compact,uniform and flat.The making process is simple and low-cost,easy to control and repeat,making it an important method to prepare the perovskite films.In this paper,we prepare the methylammonium lead bromide perovskite solar cells via vapor-assisted solution deposition method.The best concentration of PbBr2 and the best reaction time of PbBr2 and CH3NH3Br is studied to be 1 M and 20 min.Then the methylammonium lead bromide film is deposited on the mesoporous TiO2 and the C60 layer.It is revealed that the C60 layer causes more loss of incident light though the transmittance characterization.It can be seen that the thin layer is on the mesoporous TiO2 is smoother and flatter than that on the C60 layer though the SEM and AFM method.After the layers are assembled into mesoporous cells and planer cells,the best planer cell received 3.34%efficiency,while the efficiency of the best mesoporous cell is 3.53%.It can be seen that the mesoporous cells have better phone-electric property than the planer cells.In detailed research we find out that the mesoporous cells have longer carrier lifetime,lower transmission resistance and better performance,compared with the planar cells though EIS measurement.We fabricate the methylamine-lead bromide films in vacuum,nitrogen and air separately and we find out that the reaction atmosphere of vapor-assisted solution deposition method has an important influence on the growth of perovskite films.The results of SEM and AFM show that the grain size of methylamine-lead bromide film grown in nitrogen atmosphere is larger and the film is smoother compared with vacuum atmosphere,while the film formed in air has poor coverage and large roughness with many holes.Through XRD,UV-vis,steady-state PL and transient PL measurement,it can be found that the growth of methylamine-lead-bromine perovskite films in nitrogen has better crystallinity,less defects and the life of carrier is longer,which can be transported more quickly when contacting with the electron transport layer.The three kinds of perovskite films grown in the different atmospheres are assembled into batteries.The best efficiency is obtained by the mesoporous solar cell prepared in nitrogen,which is 4.88%.The short-circuit current density,the open-circuit voltage and the filling factor are respectively 5.95 mA/cm2,1.2 V,68.29%.The achieved 3.53%while the best solar cell made in air achieved the lowest efficiency of 2.25%.Through electrochemical impedance analysis and the voltage attenuation test,it is known that the lifetime of the carrier in the cells made in nitrogen is longer while the transmission resistance is smaller and the performance is better compared with the cells of vacuum condition. |
