The use of inorganic nano-semiconductor/polymer blend as the active layer for organic bulk heterojunction solar cell is an alternative to change and improve the device characteristics and performance. Effects of CdSe/P3HT composition in the blend and its loading amount in the solvent on the electrical and structural properties of active layers formed were investigated. The results of atomic force microscopy study indicated that the surface roughness of composite active layer could be controlled below 10 nm for the entire range of composite loading amount investigated in this study. The transmission line method experiments have demonstrated that the electrical percolation (p)athways could be developed at the critical loading amount of CdSe/P3HT composite, resulting in the abrupt decrease of sheet resistance and significant increase in the power conversion efficiency of ITO/PEDOT:PSS/(CdSe/P3HT)/Al solar cell. (C) 2010 Elsevier B.V. All rights reserved.