Crystalline Phase Segregation of Quantum-Dots-Passivated CH3NH3PbI3 Film via Argon Plasma Treatment

Abstract

In this study, a composite perovskite film composed of lead cesium triiodide (CsPbI3) quantum dots (QDs) and methylammonium lead iodide (CH3NH3PbI3; MAPbI3) was proposed. The CsPbI3 QDs prepared by hot-injecting were used as an anti-solvent in precursors to passivate the surface of this composite perovskite film. The further argon (Ar) plasma treatment improves the surface of the film. The effects of the powers from 100 to 200 W on the composite perovskite film structure, chemical element composition, and optical properties were studied. The experimental results demonstrate that the CsPbI3 QDs passivation boosts the ultraviolet light absorption (350–450 nm) and inhibits the formation of the PbI2 phase. Furthermore, Ar plasma treatment effectively improved CsPbI3 QDs passivation on MAPbI3 film. The powers lower than 140 W cause C=O bonds to dissolve and coordination bonds to form between OA carboxyl moieties and undercoordinated Pb2+ ions. At 160 and 140 W, the obvious crystal phase segregation and a decrease in light absorption are observed, respectively. Meanwhile, the strong bombardment of Ar ions at higher than 160 W causes the severe degradation of MAPbI3 film.