Preparation of CuIn(S_xSe_1–x)₂ thin films with tunable band gap by controlling sulfurization temperature of CuInSe₂

In this paper, polycrystalline CuIn(S_xSe_1–x)₂ thin films with tunable x and E_g (band gap) values were prepared by controlling the sulfurization temperature (T) of CuInSe₂ thin films. X-ray diffraction indicated the CuIn(S_xSe_1–x)₂ films exhibited a homogeneous chalcopyrite structure. When T increases from 150 to 500 °C, x increases from 0 to 1, and E_g increases from 0.96 to 1.43 eV. The relations between x and E_g and the sulfurization process of CuIn(S_xSe_1–x)₂ thin films have been discussed. This work provides an easy and low-cost technique for preparing large area absorber layers of solar cell with tunable E_g.