Sustainable fabrication of ultralong Pb(OH)Br nanowires and their conversion to luminescent CHNHPbBr nanowires

The fabrication of lead halide perovskites involves different types of organic solvents, which are not only harmful to the environment but also expensive. Herein, we present an ultimately green process to prepare CH 3 NH 3 PbBr 3 (MAPbBr 3 ) nanowires without using any organic solvents, acids, and alkalis. According to the formula of Pb(OH)Br, only PbBr 2 and water are used to synthesize Pb(OH)Br. Subsequently, the Pb(OH)Br nanowires are converted into MAPbBr 3 nanowires via a thermal evaporation technique ( i.e. , exposing Pb(OH)Br nanowires to MABr vapor). The prepared MAPbBr 3 nanowires show comparable optical properties to those prepared using organic solvents. Such an ultimately green fabrication method can alleviate the environmental concerns and reduce the cost of perovskite commercialization. Ultralong Pb(OH)Br nanowires can be spontaneously prepared in a pure aqueous solution and then transformed into perovskites with shape preservation.