Influence of light intensity on the performance of CdS thin-film photoelectrochemical cells

The following study depicts the effect of light intensity on the performance of CdS thin-film photoelectrochemical cells. The thin films exhibit strong absorbance over the UV and visible regions, with an absorption edge located at approximately 510 nm, corresponding to the bulk CdS directly exhibiting a bandgap. The bandgap of approximately 2.46 eV obtained by the Tauc plot analysis is in agreement with known values and is very important for the optimization of the optoelectronic properties of the material. This calculation of d values is obtained from the XRD pattern. From the measurements, it was found that the crystallite size varied in the range of 25–30 nm. These SEM images show the surface morphology of the film, which confirmed its homogeneity with large agglomerates of CdS, in which nanosized particles were embedded. The n-type semiconducting nature of the films is thus confirmed by J–V measurements under illumination with different light intensities ( \({2.5\times 10}^{-3}\) ${2.5\times 10}^{-3}$ , \({5.0\times 10}^{-3}\) ${5.0\times 10}^{-3}$ , \({10.0\times 10}^{-3}\) ${10.0\times 10}^{-3}$ , and \({20.0\times 10}^{-3}\) ${20.0\times 10}^{-3}$ Wcm⁻²). The variation in key PEC performances, short-circuit current density (J_sc), open-circuit potential (V_oc), fill factor (FF), and conversion efficiency (η), is dependent on light intensity. The results revealed that the logarithmic dependency of the light intensity on the photocurrent resulted in a good linear regression fit, with an R² of approximately 0.97 and a relatively high R². However, nonuniform light absorption, increased recombination rates, and thermal effects at high light intensities all result in decreased efficiencies. This finding argues in favor of optimum light intensity management for better PEC cell performance.