Investigation of the potential solar cell application of Cs2AgBiBr6 lead-free double perovskite

Abstract

Methylammonium lead halides are outstanding photoactive perovskites for energy conversion devices. Irrespective of excellent performance, chemical instability, and toxicity remain challenges for their potential acceptance. Recently, owing to the nontoxicity and high relative stability of Cs2AgBiX6 (X = Cl or Br), double perovskites have found as a significant substitution to the lead-based absorber for perovskite solar cells (PSCs). Especially, Cs2AgBiBr6 has appeared to be an alternative to perovskite based on lead. The unique features of Cs2AgBiBr6 like nontoxicity, higher stability, multifunctionality, and optoelectronic properties lead to promising lead-free double perovskite. In this study, the potential solar cell application of lead-free Cs2AgBiBr6 double perovskite absorber is studied through density functional theory and via experimental and theoretical analysis. SACPS-1D simulation is used to design a PSC of FTO/SnO2/Cs2AgBiBr6/Cu2O/Au cell configuration to study the effect of various parameters. The device simulation is initially optimized and validated under the experimental counterpart and then the other parameters for the material such as the absorber thickness, defect density, operating temperature, series resistance, bandgap, etc are improved to deliver a better performance. Further, the suggested device simulation is performed with various electron transport layers (ETLs) of SnO2, TiO2, and ZnO revealing these ETLs may be adopted for PSCs composed of lead-free Cs2AgBiBr6 absorber. Final optimized Cs2AgBiBr6 has a power conversion efficiency of 16.63%, 16.85%, and 16.79%, open-circuit voltages of 1.511, 1.508, and 1.510 V, current densities of 15.76, 15.71 and 15.75 mA/cm2, and fill factors of 69.84, 71.1 and 72.52 with ETLs of SnO2, TiO2, and ZnO, respectively.