High-efficiency Sb2Se3 thin-film solar cells based on Cd(S,O) buffer layers prepared via spin-coating

Abstract

CdS films prepared via chemical bath deposition exhibit extremely good performance as a buffer layer of chalcogenide solar cells. However, their commercial application is very limited because of the production of a large amount of wastewater containing cadmium. In this study, we develop an efficient way to prepare CdS films using the spin-coating technique. The spin solution is anhydrous, and the oxygen content can be well controlled by changing the Cd/S content ratio in the solution. The crystal structure, morphology, and optical and electrical properties of CdS films with different Cd/S content ratios are characterized. The effect of the oxygen content on the device performance is investigated. We find that the introduction of an appropriate amount of oxygen can improve the carrier transport efficiency by decreasing the interface recombination. The spin-coated CdS films have good coverage of the substrate for film thicknesses below 50 nm. By the optimizing of Cd/S content ratio, we achieve an improved efficiency of 5.76% for the Sb2Se3 solar cells. This preparation technique is sufficiently simple for large-scale processing and produces much less wastewater containing cadmium; thus, it is promising for application to future large-scale solar cell production.