Study on the Key Parameters Affecting the Power Conversion Efficiency of Cs2AgBiBr6-Based Perovskite Solar Cells

Abstract

The lead-free halide double perovskite material A2BB’X6 represented by Cs2AgBiBr6, has higher potential as a photovoltaic material since it has good electronic and optical properties in recent years. However, the highest power conversion efficiency (PCE) achieved for solar cells made with Cs2AgBiBr6 as the light-absorbing layer in experiments is only 2.51%. To investigate this phenomenon, we used the Solar Cell Capacitance Simulator (SCAPS) simulation software to build five solar cell models with the structure of FTO/ZnO/Light-absorbing layer/Cu2O/Au based on different light-absorption layer materials. Two reasons causing the low PCE of Cs2AgBiBr6 solar cells were identified. On the one hand, interlayer defects in Cs2AgBiBr6 film synthesis significantly decreased the fill factor (FF), thereby reducing the quantum efficiency (QE). On the other hand, Cs2AgBiBr6’s larger indirect bandgap resulted in a narrower absorption range. Additionally, it was demonstrated that adjusting the material thickness and alloying method could, respectively, improve the two aforementioned issues. When the thickness of the light-absorbing layer material was 300[Formula: see text]nm, the FF increased from 39.88% to 55.01%, resulting in an optimal PCE of 3.88% for the solar cell. Alloying increased the short-circuit current ([Formula: see text]) from 8.44[Formula: see text]mA/cm2 to 21.24[Formula: see text]mA/cm2, leading to a simulated PCE increase of 8.92% for solar cells based on Cs2NaSb[Formula: see text]In[Formula: see text]I6. This work, from the perspective of device simulation, is highly significant for improving the photoelectric conversion efficiency of Cs2AgBiBr6-based perovskite solar cells in experimental settings. It offers new insights for optimizing solar cell efficiency.