Methyl Ammonium Doping Enhances the Photocatalytic Activity of Lead‐Free Halide Double Perovskite (Cs 2 AgBiBr 6 )

Halide double perovskites are emerging as a promising class of Pb‐free perovskite materials owing to their remarkable optical properties. However, the photo‐responsive performance of these materials can be further enhanced through appropriate doping strategies. This study explores the effect of methylammonium (MA) cation doping on a lead‐free halide double perovskite for photocatalytic oxidation of alcohol. Here, the pristine (Cs 2 AgBiBr 6 ) and organic cation‐doped perovskites (MA) 0.4 Cs 1.6 AgBiBr 6 and (MA) 0.6 Cs 1.4 AgBiBr 6 were synthesized by modified antisolvent‐assisted precipitation, and their electronic, as well as photocatalytic, properties were investigated. The photocatalytic activity of the three perovskite materials was examined by analyzing 1‐phenylethanol to acetophenone conversion under blue light‐emitting diode (LED) ( λ = 427 nm) illumination. The MA‐doped perovskite showed more than twofold improvement in the percent conversion of 1‐phenylethanol to acetophenone compared to the pristine Cs 2 AgBiBr 6 . The shift in the valence band (VB) and conduction band (CB) energy levels, improvement in photocurrent response, and decrease in charge‐transfer resistance of the doped halide perovskite compared to the pristine Cs 2 AgBiBr 6 play key roles in the higher percentage conversion in the alcohol oxidation reaction.