Electrodeposition of Cu(In,Ga)Se<sub>2</sub> Crystals on High-Density CdS Nanowire Arrays for Photovoltaic Applications

High-density and single-crystalline CdS nanowires were grown on fluorine-doped tin oxide (FTO)/soda-lime glass substrates using Bi catalysts via the so-called solution−liquid−solid (SLS) mechanism. Through a series of voltage loading steps, high-quality Cu(In,Ga)Se<sub>2</sub> (CIGS) light absorption layers were electrochemically deposited on the CdS window layers and subsequently selenized at 400 °C to form photovoltaic cells. Due to the one dimensionality and single crystallinity of the CdS nanowires, the carrier collection efficiency could be improved. The resulting CIGS/CdS nanowire solar cells showed a light energy conversion efficiency of ∼6.18% under AM 1.5 conditions (<i>I</i> = 100 mW/cm<sup>2</sup>), which is ∼28.7% higher than that of the equivalent CIGS solar cells containing chemically deposited CdS thin film as a window layer.