A novel tandem structure composed of dye sensitized solar cell (DSC) and CuInGaSe2 (CIGS) solar cell shows the potential to increase conversion efficiency by fully utilizing the sunlight. In our research, a tandem solar cell with a high open-circuit voltage of 1.15 V and a conversion efficiency of 10.46%, which is both larger than that of DSC and CIGS solar cell has been prepared. To further increase the tandem efficiency, equivalent circuit analysis is carried out to find out the corresponding factors. It is also found that there is limitation for the tandem structure to increase the efficiency. Transmittance and performance of DSC top cell are found to be the essential factors which determine the tandem effect. (C) 2010 Elsevier B.V. All rights reserved.