Improvement of Cu(In,Ga)Se2 solar cell performance by thiourea treatment

We investigated the effects of a thiourea treatment performed to the absorber of Cu(In,Ga)Se-2 (CIGS) solar cells. The thiourea treatment successfully improved the open-circuit voltage, fill factor, and conversion efficiency of the solar cells. Reduced ideality factor and reverse saturation current density demonstrated that the suppression of carrier recombination contributed to the improvement in solar cell performance. Increased intensity in cross-sectional electron-beam-induced current measurements confirmed the improved film quality with the thiourea treatment. Additionally, an enhanced carrier density observed with the treatment suggests the passivation of donor-type defects. These results indicate that the thiourea treatment is promising to improve the absorber quality and enhance the performance of CIGS solar cells.