We fabricated planar heterojunction (PHJ) solar cells with enhanced efficiencies by introducing fullerene (C-60) interlayers of thicknesses of 0, 3, 7, and 10 nm between the air-stable amorphous compact titanium oxide (TiOx) and CH3NH3PbI3 layers. The modified morphology obtained by inclusion of C-60 improved the surface energy properties of the cells in terms of enhanced photocurrent. The optimum thickness of the C-60 interlayer was 7nm, for which a maximum power conversion efficiency of 9.51% was obtained.