Influence of mole concentration on nano crystalline Bi-doped CuInS2 thin films with the temperature by chemical spray method

Abstract Copper Indium Disulphide (CuInS 2 ) is an efficient absorber material for photovoltaic and solar cell applications. In this paper Bi (0.02 and 0.03 M) doped CuInS 2 thin films are (Cu/In = 1.25) deposited on to glass substrates in the temperature range 300–400 °C. The optical bandgap energy ( E g ) increases with the increase in temperatures for both 0.02 and 0.03 M samples. SEM photographs reveal the formation of a large number of flower like small crystals of size ranging from 70 to 200 nm. The EDAX results confirm the presence of Cu, In, S and Bi in the films. All the films present low resistivity ( ρ ) values and exhibit semiconducting nature. Hence, Bi species can be used as a donor and acceptor impurity in CuInS 2 thin films to fabricate efficient solar cells, photovoltaic devices and good IR Transmitters.