Room-Temperature Perovskite Phase Transition of CsPbI for PV Manufacturing on Flexible Substrates.

Printing perovskite films typically involves a high-temperature treatment exceeding 150 °C, which limits the manufacturing of flexible devices. All inorganic CsPbI perovskite is particularly promising for commercialization due to its high thermal stability. Herein, we discovered that when using DMF precursors containing CsI and HPbI for fabricating CsPbI films, an isopropanol (IPA) antisolvent bath immersion treatment of the wet films can enable a direct and rapid formation of optically active perovskite black phases at room temperature without annealing.