Effects of electron transport layer type on the performance of Pb-free Cs2AgBiBr6 double perovskites: a SCAPS-1D solar simulator-based study

Recently, due to the superior stability and lower risk of toxicity, the development of Pb-free halide double perovskite materials has revived excellent interest. In this work, Pb-free perovskite solar cells (PSCs) with ITO/ETL/Cs2AgBiBr6/Cu2O/Au multilayer structures with Cs2AgBiBr6 double perovskite as the solar light absorber layer, some electron transport layers (ETLs) and Cu2O as a hole transport layer have been introduced. Then, the effects of various thicknesses of the absorber layer and also ETL materials, like ZnO, C-60, CdS, SnO2, phenyl-C-61-butyric acid methyl ester (PCBM), and TiO2, on the device performance (including photoelectronic conversion efficiency (PCE), fill factor (FF%), short circuit current density (Jsc), and open-circuit voltage (V-OC)) were examined with the help of a solar cell simulator (SCAPS-1D). It is noteworthy that, in the case of all ETL materials, the optimal thickness of the absorber layer was determined to be 400 nm. Then, the maximum PCE values of 20.08%, 17.63%, 14.07%, 12.11%, 14.94%, and 18.83% were obtained for the solar cells containing ZnO, C-60, CdS, SnO2, PCBM, and TiO2 as the ETL, respectively. These results show that designing/developing Pb-free halide double perovskite devices having comparable PCEs with the Pb-based PSCs is feasible, provided that proper/compatible materials will be used in the multilayer structure of the next generations of solar cells.

Automated summary

By introducing Pb-free perovskite materials and multilayer structures, this study successfully develops solar cells with comparable photoelectric conversion efficiency. Experimental results show that the device performance is best when the thickness of the absorber layer is 400nm, regardless of the ETL material used.