Effects of compression and controlled selenization on powder-fabricated Cu (In,Ga)Se2 thin films
Cu(In,Ga)Se2 thin films have been used as a light absorbing layer in high-efficiency solar cells. Among many methods, the powder process for fabricating Cu(In,Ga)Se2 thin films is advantageous, due to its simplicity and minimal usage of materials. However, Cu(In,Ga)Se2 layers produced by the powder process often result in high porosity and small grain sizes, which has been a significant barrier to wide application. In this report, we demonstrate that simple compression of the Cu(In,Ga)S2 powder coat and a cost-efficient selenization using a mixture of Se and Al2O3 can reduce porosity and enlarge the grain size. It is surmised that improved particle packing density in the powder coats, in addition to sintering with a steady supply of Se vapor, synergistically enhances highly sintered Cu(In,Ga)Se2 thin films.