This work is supposed to expand the concept of solvent induced crystallisation of donor poly(3-hexylthiophene) (P3HT) polymer, to the photoactive blend of inverted organic solar cells. With the optimised concentration of cyclohexanone (CHN) co-solvent and ageing period of 2 h for the active layer precursor solution, the power conversion efficiency of a typical device increased to 3.09% compared with 2.77% efficiency achieved in a similar kind of inverted device without CHN modification. This improvement of 10% in the efficiency of inverted device with CHN addition was related to the increased current density and fill factor of the device. Increased P3HT crystallinity for efficient photo-absorption and commensurate vertical concentration gradient observed in the P3HT fractions of the blend for efficient hole transport is possibly responsible for the betterment of the photovoltaic parameters in the modified device.