High efficiently CsPbBr3 perovskite solar cells fabricated by multi-step spin coating method

We have demonstrated that the preparation technology of high-quality CsPbBr3 perovskite thin film based on multi-step spin coating method by using solvent engineering. We effectively avoided that both heterogeneous nucleation on the substrate surface and homogeneous nucleation on the surface could form a large number of grains during spin coating. The multi-step spin coating method can form the layered and superimposed CsPbBr3 perovskite films by spin coating for many times with different annealing temperatures, which can form CsPbBr3 phase with consistent particle size and vertical distribution. Can And Thus, it can greatly improve the efficiency of carrier extraction and collection, and comprehensively enhance the PCE of the CsPbBr3 solar cells. Moreover, the multi-step spin coating method can effectively fabricate the required thickness of CsPbBr3 perovskite films and eliminate the non-CsPbBr3 phase in the process of film formation. The results showed the power conversion efficiency of CsPbBr3 perovskite solar cells with annealing temperature of 100 °C is up to 10.02% with the open circuit voltage (Voc) of 1.47 V, the short circuit current density (Jsc) of 8.22 mA/cm2 and the filling factor (FF) of 83%, which is one of the highest reported efficiencies of the CsPbBr3 perovskite solar cells so far. The efficiency basically retained the original value when the optimal CsPbBr3 soalr cell was placed in the air at room temperature after 350 days. Meanwhile, the efficiency of CsPbBr3 soalr cells at 120° C was decreased only by 10%, showing excellent thermal stability.