The effects of the inclusion of reduced graphene oxide (RGO) in TiO2 layers on performance of perovskite solar cells were systematically investigated. For this purpose, a wet chemical approach was examined to embed graphene oxide (GO) across the thickness of compact TiO2 (cTiO(2)) and mesoporous TiO2 (mTiO(2)) layers, which was followed by a thermally driven in situ conversion from GO to RGO. The presence of RGO at loadings of 0.15 wt % in the cTiO(2) layer and of 0.015 wt % in the mTiO(2) layer led to a power conversion efficiency (PCE) from 6.6% to 9.3% by 40% increase.