Efficiency improvement of CTL-free PSCs based on Sn-/Pb-perovskite heterojunction: a numerical approach

Perovskite solar cells (PSCs) with no charge transport layer (CTL) have drawn great attentions due to their simple device structure and low cost. However, the low efficiency hampers their practical applications. In the study, a novel FASnI 3 /MAPbI 3 heterojunction structure is proposed to replace the conventional MAPbI 3 absorber layer for efficient CTL-free PSCs. The numerical tool SCAPS-1D is employed to optimize the proposed structure taking into account multiple device and material parameters, such as layer thickness, doping concentration of MAPbI 3 , electron affinity of FASnI 3 and back electrode work function. After optimization, the highest yielded efficiency of the FASnI 3 /MAPbI 3 bilayer structure is 25.34%, which is 54.9% relatively higher than the conventional MAPbI 3 single-layer structure (with an optimal efficiency of 16.36%). The simulation results demonstrate the huge potentials of proposed FASnI 3 /MAPbI 3 heterojunction for constructing efficient CTL-free PSCs and provide inspirations for the future development of CTL-free PSCs.