Organic–inorganic CH 3 NH 3 PbI 3 (MAPbI 3 ) inverted structured perovskite films were prepared using Pb(CH 3 COO) 2 (Pb(OAc) 2 ) and CH 3 NH 3 I (MAI) as source materials. The structural, optical and photoelectronic properties of the MAPbI 3 films varied with the Pb(OAc) 2 /MAI molar ratio. It was found that the Pb(OAc) 2 /MAI molar ratio greatly influenced the structure and morphology of the MAPbI 3 films. A suitable amount of excessive Pb(OAc) 2 (about 5 mol% excessive Pb) in the solution made the film smoother with improved film crystallinity. This resulted in enhanced power conversion efficiency (PCE). However, for films derived from solution with low Pb(OAc) 2 /MAI or high Pb(OAc) 2 /MAI ratio, defects such as pits or pinholes were easily formed with low crystallinity, and hence decreased the lifetime of the carriers and photoelectrical properties of the final solar cells. Using a solution with 5% excessive Pb, inverted structured CH 3 NH 3 PbI 3 perovskite solar cells with PCE of nearly 14% were obtained. [ABSTRACT FROM AUTHOR]