Performance optimization of quasi-interdigitated back-contact perovskite solar cells

Abstract

In this work, a quasi-integrated back contact (QIBC) perovskite solar cell (PSC) consisting of a perovskite layer based on a ternary cationic polyhalide (CsFAMAPbIBr), a titanium oxide (TiO2) electron-transport layer (ETL) and a copper thiocyanate (CuSCN) hole-transport layer (HTL) was studied. During the study, a two-dimensional optoelectric model of the perovskite device was created using the COMSOL Multiphysics software package. The experiments were conducted in two different cases, i.e., when the light was incident on a transparent absorber layer located on the ETL layer side (front-side) and directly on the perovskite layer (rear-side). First, a generation velocity distribution map was obtained for both cases. The optical generation of charge carriers in the perovskite layer was calculated based on the electromagnetic field distribution. The distribution and flow of optical energy inside the structure were described by a time-averaged Poynting vector. A drift-diffusion model for electrons and holes was developed, and the effect of electrical parameters on the PCE was evaluated using the length-averaged generation value obtained from optical simulation. During the study, the effect of the surface defect density between the perovskite layer and the electron transport layer, the bulk defect density in the perovskite layer, and the electron mobility on the device efficiency was studied. For each case, the current–voltage characteristics (J–V) and power conversion efficiency were calculated. It was found that for large values of defects at the perovskite-ETL interface, the efficiency decreases significantly, and when light is incident from above and below, the power conversion efficiency decreases with increasing volume trap density, and the efficiency of the PCE increases with increasing electron mobility. Based on the results obtained, the sensitivity of the QIBC PCE to defects and stability to parameters were determined, as well as the dependence of the direction of light incidence from below or above.