Bandgap-tunable double-perovskite thin films by solution processing

Abstract Narrowing the bandgap of lead-free double-perovskite Cs 2 AgBiBr 6 is required for using this material in future photovoltaics. Herein, we demonstrate a bandgap engineering of Cs 2 AgBiBr 6 by introducing Sb to substitute up to 75% of Bi via a versatile solution-processed method in dimethyl sulfoxide at 180 °C. The resultant Cs 2 AgSb x Bi 1− x Br 6 ( x  = 0, 0.25, 0.50, 0.75) thin films possess high crystallinity and good thermostability. Moreover, the Sb substitution enables an obvious bandgap reduction of 0.25 eV. The fabricated solar cell using the Cs 2 AgSb x Bi 1− x Br 6 ( x  = 0.25) thin film obtained an increased performance than the reference Cs 2 AgBiBr 6 . The effective bandgap narrowing via a facile solution method might accelerate the development of Cs 2 AgBiBr 6 -based materials for photovoltaic applications.