Bandgap-tunable double-perovskite thin films by solution processing. (September 2019) - Liu, Yuan
Graphical abstract: In this study, we present a facile solution-processed method on controlled synthesis of the Cs2 AgSb x Bi1− x Br6 thin films with Sb substitution. The Cs2 AgSb x Bi1− x Br6 thin films were successfully prepared. The resulting Cs2 AgSb x Bi1− x Br6 thin films exhibited high purity, crystallinity, and thermostability. Moreover, the Sb substitution effectively reduced the E g of Cs2 AgSb x Bi1− x Br6 from 2.22 to 1.97 eV. The effective bandgap narrowing via facile solution-processed method might facilitate the development of Cs2 AgSb x Bi1− x Br6 thin-film photoabsorber. Abstract: Narrowing the bandgap of lead-free double-perovskite Cs2 AgBiBr6 is required for using this material in future photovoltaics. Herein, we demonstrate a bandgap engineering of Cs2 AgBiBr6 by introducing Sb to substitute up to 75% of Bi via a versatile solution-processed method in dimethyl sulfoxide at 180 °C. The resultant Cs2 AgSb x Bi1− x Br6 ( 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 Cs2 AgSb x Bi1− x Br6 ( x = 0.25) thin film obtained an increased performance than the reference Cs2 AgBiBr6 . The effective bandgap narrowing via a facile solution method might accelerate the development of Cs2 AgBiBr6 -based materials for photovoltaic applications.