Spectral Response Enhancement of the CdS/CdTe Solar Nano-Structured Cell Using ZnO Window Layer

N-type ZnO top layer in view of improving the spectral response in the lower wavelength range (300–500 nm) has been integrated into the novel nanopillar-based n-CdS/p-CdTe solar cell. The device performance has been studied using physics-based device Simulator TCAD Silvaco. It has been found that integrated ZnO layer owing to its wide bandgap has not only improved the spectral response, and short circuit current density, but large valence band offset (VBO) energy (
$\Delta {E}_{\text {v}} = 1$
eV) has also caused the increase in the open-circuit voltage (
${V}_{\text {oc}}$
) and efficiency (
$\eta$
) of the device. Besides, comparison of the device performance parameters such as short circuit current density (
${J}_{\text {sc}}$
), open-circuit voltage (
${V}_{\text {oc}}$
), and solar cell conversion efficiency (
$\eta$
) of the proposed device with its equivalent device structure without ZnO layer has shown the improvement by 13.96%, 3.09%, and 16.75%, respectively. Besides, added ZnO layer does not contribute to any series resistance leaving fill factor (FF) unaltered.