The effect of H2O2 treatment on the optoelectronic property of the poly(3-hexylthiophene) doped with reduced graphene oxide sheets (P3HT:RGO)/Si-nanowire (SiNW) arrays/n-type Si diode was examined. SiNW surface passivation influences device performance. Compared to P3HT:RGO/SiNWs/n-type Si diodes, P3HT:RGO/H2O2-treated SiNWs/n-type Si diodes exhibit much higher photoconductivity. The results revealed that SiNW surface passivation influences the photoconductivity by reducing the number of electron traps that serve to decrease the photocurrent time constant. High responsivity thus originates from efficient light absorption and carrier collection. (C) 2014 Elsevier B.V. All rights reserved.