Enhancement of solar cell efficiency through tailored electrodeposited seed layers and CdS: O surface texturing

This study focuses on a surface texturing technique using electrodeposition to enhance the junction properties of thin film solar cell structures. The CdS/CdTe solar cell structure was used to demonstrate this concept, focusing on the thermally evaporated oxygenated CdS layer deposition on the textured layer of electrodeposited CdS seeds, ultimately improving the CdS/CdTe junction properties and solar cell performance. Deposited CdS seeds have grown after the deposition of the thermally evaporated CdS: O layer and subsequent annealing. Optical characterizations of CdS seed layers and subsequent CdS layer stacks revealed that seed layers deposited with an applied potential of -680 mV exhibit a significant blue shift and a steep band edge. These optical characteristics were confirmed by the calculated bandgap values. Morphological characterizations exhibited an increment of seed density with applied potential. Additionally, an improved seed size and seed growth upon layer deposition by thermal evaporation were observed for the seeds deposited at -680 mV. Structural characterizations of seed layers via X-ray diffraction followed by Rietveld and Pawley refinements confirmed the optical bandgap variation. X-ray photoelectron spectroscopy validated the results obtained for the optical bandgap with the analysis of surface chemistry of seed layers. These optimized CdS seed layers facilitated subsequent thermal evaporation of CdS: O thin films and the fabrication of CdS/CdTe solar cells. The electrical characterizations emphasized that the solar cells deposited using the seed layer at -680 mV yield better electrical properties.