Precursor engineering for high-quality Cs2AgBiBr6 films toward efficient lead-free double perovskite solar cells

We report a facile BiBr₃(DMSO)₂ adduct process to produce high-quality Cs₂AgBiBr₆ films with large grains for the first time, which leads to an enhancement of over 40% on the PCE of Cs₂AgBiBr₆-based solar cells compared to that of the control sample.