Periodic voltammetry as a successful technique for synthesizing CdSe semiconductor films for photo-electrochemical application

Polycrystalline n-type CdSe thin films were deposited from aqueous bath at room temperature by periodic voltammetry for use in photo-electrochemical (PEC) solar cells. The influence of periodic scans on the functional properties of the chalcogenide films was thoroughly investigated through electron microscopy (SEM), X-ray diffraction (XRD), UV–visible spectrometry, and electrochemical techniques. The film thickness increases with the number of periodic scans, and the spectral measurements identify the optical band gap in the range 1.55–1.72 eV. The CdSe films show typical X-ray diffraction patterns of hexagonal crystal structure with particle size 20–30 nm, uniformly distributed throughout the matrix. PEC characteristics including photo-current density, conversion efficiency (η), fill factor (FF), and durability of the films were evaluated by the help of respective electrochemical techniques. The voltammetric cycle number was optimized which enable to identify the best CdSe film exhibiting photo-conversion efficiency of ~1% with minimum photocurrent decay.