High-efficiency CIGS solar cells with modified CIGS surface

CIGS films were treated in In–S aqueous solution for high-efficiency CIGS solar cells. The In–S aqueous solution contained InCl3 and CH3CSNH2 (thioacetamide). The In–S treatment modified the CIGS surface favorably for high-efficiency CIGS solar cells as evidenced by the increase in Voc, Jsc and FF. The In–S treatment formed thin CuInS2 layer on the CIGS surface which contributes to the high efficiency and stable performance of the CIGS solar cell. The best cell showed an efficiency of 17.6% (Voc=0.649 V, Jsc=36.1 mA/cm2 and FF=75.1%) without any annealing and light soaking before I–V measurement.