Efficient organic solar cells based on the blends of poly (3-hexylthiophene) (P3HT):fullerene derivative[6,6]-phenyl-C(61) butyric acid methyl ester (PCBM) composites have been fabricated by using the sputtered amorphous chromium oxide (ACO) film on fluorine-doped tin oxide (FTO) coated glass substrates as a hole-transporting layer (HTL). Through ACO layer sputtering temperature, film thickness and oxygen flow ratio optimization, the highest power conversion efficiency of 3.28% of FTO/ACO/P3HT:PCBM/Al solar cells on glass has been achieved under AM1.5G 100 mW/cm(2) illumination. It is found that the device with 10 nm thick ACO sputtered at 473 K and oxygen flow ratio f(O(2)) (O(2)/O(2) + Ar) = 40% shows the best photovoltaic properties. The photovoltaic properties in these devices are discussed in terms of the band diagrams and series resistance of the devices, and characteristics of ACO HTL It is concluded that ACO is a suitable alternative to poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) as a HTL. (c) 2011 Elsevier B.V. All rights reserved.