LAUSR

Methylammonium lead iodide (CH3NH3PbI3) has emerged as a superior light-absorbing material for perovskite solar cells, mainly because of its excellent optical and electronic properties. However, insufficient long-term stability of CH3NH3PbI3 has severely hindered its practical applications. The direct addition of 5-ammonium valeric acid iodide (HOOC(CH2)4NH3I or AVAI) to perovskite precursors, such as CH3NH3I and PbI2, was found to improve the stability of CH3NH3PbI3, but can limit the incorporation of AVA+ into the CH3NH3PbI3 structure because of strong competitive interactions between AVA+ and CH3NH3+ with PbI2 through the same electrostatic interactions. Here, we present an alternative approach to prepare high-quality CH3NH3PbI3 containing AVAI films via an intramolecular exchange process. The films were prepared from precursor complexes, that is, organic lead iodide complexes, by the intramolecular exchange of dimethyl sulfoxide intercalated in the complexes with CH3NH3+. Scanning electron microscopy,...