Improved ionic liquid-based mixed electrolyte by incorporating alcohols for CuIn_xGa_1-xSe₂ films deposition

BMIm-OTF (1-Butyl-3-methylimidazolium trifluoromethanesulfonate) ionic liquid and alcohols/different volume fraction of n-propyl alcohol (normal propyl alcohol) mixed electrolytes are studied for the first time. The electrochemical behaviors of CIGS are investigated by cyclic voltammetry (CV) in ionic liquid and alcohols mixed electrolytes, respectively. The morphological properties of CIGS films are detected using scanning electron microscopy (SEM). Raman spectra at around 175 cm^− 1 are normalized to the dominant A₁ mode. The structural properties and various phases are determined by using X-ray diffraction (XRD) and Raman techniques. The XRD results indicate that the CIGS phase formed by incorporating Ga into the CIS phase. The Cu_1.00In_0.45Ga_0.1Se_2.26 thin films present as a p-type semiconductor and the Ga/(Ga + In) = 0.18 which electrodeposited from BMIm-OTF/n-propyl alcohol (30 vol%) mixed electrolytes. The band gap of the obtained CIGS thin film is approximately 1.48 eV, as measured using UV–visible absorption spectra. The carrier concentration and average Hall coefficient of the CIGS thin films are 6.366 × 10¹⁹ cm^− 3 and 9.806 × 10^− 2 cm³/C, respectively.