Effect of ultra-thin ZnS passivation using ALD technique on the performance of heterojunction solar cells

Hybrid solar cells (HSCs) using poly (3,4-ethylenedioxy-thiophene) polystyrene sulfonate (PEDOT:PSS) and nsilicon provide heterojunctions with the potential of light trapping, cost effectiveness, and high efficiency. However, charge recombination at rear interface hampers built-in potential and power conversion efficiency (PCE). Here, a superior, conformal, and uniform ultra-thin layer of Zinc sulfide (ZnS) is deposited on rear interface using atomic layer deposition (ALD) technique. The ALD-deposited ZnS thin layer serves as a passivation, electron conductive, and hole-blocking layer. The optimized HSCs exhibit a remarkable PCE of 12.37 % alongside a high open-circuit voltage of 0.625 V and a substantial fill factor of 71.5 %. These advancements stem from enhanced back junction quality between n-Si and electrode. The outcomes demonstrate an effective suppression of charge recombination and enhanced charge transfer facilitated by ALD-deposited ZnS thin layer, resulting an improved photovoltaic performance.