Fabrication of single phase CsPbBr3 films via in situ metal reaction

Inorganic perovskite CsPbBr3 is a suitable candidate owing to its excellent stability and outstanding visible light absorption. However, it is a huge challenge to fabricate single phase CsPbBr3 films. Herein, we developed an in situ metal reaction strategy to fabricate single phase CsPbBr3 films by reacting Pb precursors with CsBr/HBr in methanol solution. The thickness of the sputtered Pb film plays a key role in inhibiting the formation of a secondary CsPb2Br5 phase. The results indicate that the single phase CsPbBr3 films can be obtained by using below 40 nm of the sputtered Pb films, and the single phase CsPbBr3 device architecture exhibits 4.08% power conversion efficiency. This device can retain over 95% of the initial efficiency after 30 days of storage without packaging in an ambient environment.