The Growth and Structural Characterization in Sol–Gel Derived CuIn1–xGaxSe2 Thin Films by Controlling pH-Value

Cu(In,Ga)Se-2 thin-film samples were derived at different pH-values changing from 1 to 4 via sol-gel dip coating technique to obtain cost-effective polycrystalline thin film after annealing at 150 degrees C in air. The structural characterization and the physical properties (such as optical and electrical properties) were investigated for different pH-values. The optimum optical properties were determined to obtain a suitable absorber material. The favourable energy band gap and electrical conductivity were determined by controlling the pH-value of the film solution between 1.5-2.0 pH-value to use them at economical optoelectronic applications. The increase of pH-value presented the relation between the electrical conductivity and optical absorbance. The increase of pH-value to similar to 2 contributed the increase of the electrical conductivity. The minimum optical band gap (at 1.24 eV) was obtained at 2 pH value.