Photoelectrochemical performance of aluminum-doped AgIn₅S ₈ electrodes created using chemical bath deposition

A solution growth method for the deposition of Al-doped silver-indium-sulfide film electrodes is presented. Structural, optical, and photoelectrochemical (PEC) properties of samples were studied as a function of Al content. An X-ray diffraction pattern of the cubic spinel AgIn ₅S₈ phase was obtained for the undoped sample. No Al alloys or other binary compounds that included the Al element were present in Al-doped samples. Images from a scanning electron microscope and atomic ratios of elements in samples from the energy dispersion analysis of X-ray revealed a change of surface morphology and composition for Al-doped samples. The direct band gaps and thicknesses of samples prepared in this study varied from 1.78 to 1.90 eV and from 391 to 293 nm, respectively. The carrier concentration and mobility of samples determined from Hall measurements are in the ranges of 1.02 × 10¹³-1.97 × 10¹⁴ cm^{- 3} and 16-75 cm²/Vs, respectively. The maximum photo-enhancement current density of samples reached 3.22 mA/cm² at an external potential of + 1.0 V vs. an Ag/AgCl reference electrode in an aqueous solution containing S ^2- and SO₃^2- ions under illumination using a 300 W Xe lamp system. The experimental results show that Al doping improves the performance of AgIn₅S₈ photo-absorber for the PEC applications with an Al/(Al + In) molar ratio of 0.03 in samples.