Improvement of Cs-(FAPbI3)0.85(MAPbBr3)0.15 Quality Via DMSO-Molecule-Control to Increase the Efficiency and Boost the Long-Term Stability of 1 cm2 Sized Planar Perovskite Solar Cells

Abstract

While interfacial and grain-boundary passivation presently attract enormous research interest for perovskite solar cells (PSCs), the improvement of Cs-(FAPbI3)X(MAPbBr3)Y bulk quality still lacks systematical study, especially for constructing polycrystalline layers in planar configurations. Here, a DMSO-molecule-process for improving the quality of Cs-(FAPbI3)0.85(MAPbBr3)0.15 is developed, where the molar ratio of precursors, the kind of anti-solvents, and speed-time profiles are found critical. The optimized treatment significantly enhanced the crystal orientation, grain size, surface roughness, photo-response, carrier lifetime, and contact potential difference of absorbers. Cs-(FAPbI3)0.85(MAPbBr3)0.15 absorbers also present superior charge transport, as well as reduced carrier recombination and decreased trap densities via DMSO-molecule-control, enabling performance improvement on both long-term stability and photovoltaic parameters of 1 cm2 PSCs. Champion planar cells demonstrated a power conversion efficiency (PCE) of 21.07% (0.159 cm2) and PCE of 19.4% (1 cm2) with negligible hysteresis. Moreover, 1 cm2 devices retained 90% of initial PCE after aging 50 days in ambient air.