High efficient solar cells are desired for the future clean power supply. Here, we report a method to improve the efficiency of the promising CNT-Si solar cells to about 10% by hydrogen peroxide (H2O2) doping. It forms hybrid solar cells consisting of numerous CNT-Si heterojunction cells and CNT-Si-H2O2 photoelectrochemical cells in parallel by dilute H2O2 doping. The quantum efficiency of the H2O2-doped solar cell is higher than that of the original cell because of the photoelectrochemical cells as well as the passivation surface. (C) 2012 Elsevier B. V. All rights reserved.