Numerical Simulation Of All-inorganic Perovskite Solar Cells And All-inorganic Perovskite/GaAs Tandem Solar Cells

Since the first report in 2009,PSCs have received widespread attention due to their high absorption coefficient,low cost,compatibility with large area and flexible technics.However,because of the volatile organic cations such as MA⁺and FA⁺,the stability of PSCs during the commercialization faces severe challenges.Then,all-inorganic PSCs with better stability have emerged.All-inorganic perovskite removes unstable organic components and also has excellent photoelectric properties,which means great prospects.At present,all-inorganic PSCs still have some problems such as high voltage loss and low PCE.Based on the carrier drift-diffusion model and transfer matrix method,Silvaco TCAD simulation platform is used to study the causes and solutions of high voltage loss and low PCE of all-inorganic CsPbIBr₂PSCs.In addition,because the all-inorganic perovskite has a suitable band gap for the fabrication of tandem solar cells,this article also explores all-inorganic perovskite/Ga As tandem solar cells.The main contents are as follows:（1）The mechanism of CsPbIBr₂ single junction devices with different thickness of absorber layer is studied by simulating EQE,net carrier generation rate,photoelectric field and quasi-Fermi level of CsPbIBr₂ devices.The absorber layer of the control device is set to 200 nm with PCE of 15.43%.By introducing the interface defect layer,the effects of energy band offset on device performance is explored.The results show that,on the one hand,the energy band offset model which introduced interface defect layer is more compatible with the experiment than control device model.On the other hand,a positive energy band offset causes a spike-like barrier in energy band at the interface,which blocks carrier transport.When the energy band offset is negative,a cliff generates at the interface of energy band and performance of devices is degraded.On this basis,the effects of different doping concentrations of the charge transport layer are studied.The results show that the proper doping concentration of the charge transport layer helps to increase build-in voltage at the interface and enable the carriers can be extracted more effectively.Moreover,results show that under the adverse conditions of the electrode work function,carriers cannot be effectively collected by ETL and HTL,resulting in a decrease in performance of devices.（2）This article explores all-inorganic perovskite/Ga As tandem solar cells.For the four-terminal configuration,CsPbI₂Br was selected as the top cell absorber layer.Then,the thickness of sub-cells absorber layer and the thickness of charge transport layers were optimized and appropriate anti-reflection coatings was introduced to the sub-cells,which reduce parasitic absorption and reflection loss of the device.Based on the study of four-terminal configuration,CsPbI_3-xBr_x with different halide compositions are used for current-matching to achieve a high-efficiency two-terminal configuration.After studying the effects of density of defects and optimizing doping concentration of Ga As base,an extremely high PCE of 30.67%is achieved based on two-terminal CsPbIBr₂/Ga As tandem solar cells.In addition,an organic-free two-terminal configuration is investigated by introducing Ni O_x as HTL to further meet the potential requirement of altitude/space application.After the current-mismatching under AM 0 spectrum is eliminated,the device obtains a greatly competitive PCE of 27.23%compared with the traditional Ga As double-junction tandem solar cells.