We present Cu(In,Ga)Se2 (CIGS) thin films grown by downward co-evaporation using a downward effusion cell. CIGS thin films were prepared using the three-stage process. A composition monitoring technique was used to precisely control the relative composition of Cu, In, Ga, and Se. In this study, the vapor pressures were measured and controlled using a vapor fluxmeter. The vapor pressures of Cu, In, Ga, and Se were ~ 3.1 × 10–5 to 4.2 × 10−5, ~ 1.3 × 10–4 to 2.0 × 10–4, ~ 2.0 × 10–5 to 3.7 × 10–5, and 3.8 × 10–4 Pa, respectively. With Cu/(In + Ga)~ 0.9 and Ga/(In + Ga)~ 0.3, the Al/ZnO/CdS/CIGS/Mo/soda lime glass (SLG) solar cell demonstrated a conversion efficiency above 12%. The ZnS/CIGS solar cells were fabricated, and their photovoltaic properties were characterized. The characteristics of the CIGS thin films were investigated using X-ray diffraction (XRD) to determine their photovoltaic properties. The construction of the downward co-evaporation system for CIGS thin-film solar cells was completed and performance tested.
Keywords: CIGS, Solar cells, Downward evaporator, Molecular flux.