Crystal phase and band edge modulation of MA- and Br-free CsFA-based perovskite for efficient inverted solar cells and minimodules

Abstract

The non-radiative voltage loss associated with traps (V_loss^(non-rad)) is the crucial factor limiting the performance of inverted perovskite solar cells (PSCs). In this study, we manipulate the crystal growth and spectral response of MA-/Br-free CsFA-based perovskite to minimize the V_loss^(non-rad) by rationally introducing methyl (methylsulfinyl)methyl sulfide (MMS) into the precursor. MMS effectively inhibits the oxidation of halide and reduces the formation of δ-phase perovskite during the phase-transformation, resulting in the formation of a high-quality perovskite film with fewer defects and reduced non-radiative recombination. Notably, a 5 nm of red-shift in the band edge of perovskite is achieved, providing an additional integrated current density of 0.24 mA/cm2. Consequently, a certified efficiency of 26.01% from the reverse scan along with a quasi-steady-state output efficiency of 25.30% is achieved for the 0.09-cm2 inverted PSC, marking the highest values for inverted PSCs based on MA-/Br-free CsFA double-cation perovskite to date. The champion device exhibits a minimal V_loss^(non-rad) of 67 mV. The present stategy is also extended to a minimodule with active area of 12.96-cm2 by delivering an efficiency of 22.67% from the reverse scan. Moreover, the target devices demonstrate great thermal and operational stability. This study offers an versatile Lewis base for regulating the crystal growth and spectral response of perovskite films, and emphasizes the significance of minimizing the V_loss^(non-rad) for high-performance inverted PSCs.