Over 7% Efficiency of Sb2(S,Se)3 Solar Cells via V‐Shaped Bandgap Engineering

Antimony chalcogenides (including Sb 2 S 3 , Sb 2 Se 3 , and Sb 2 (S,Se) 3 alloy) have emerged as promising solar absorber materials. Notably, the Sb 2 (S,Se) 3 alloy possesses continuously tunable bandgap from 1.1 to 1.7 eV, which covers the ideal bandgap for single‐junction photovoltaics governed by the Shockley–Queisser theory. Moreover, the bandgap gradient provides effective ways for photogenerated carriers collection and has the potential for high‐efficient Sb 2 (S,Se) 3 alloy solar cells. Herein, a V‐shaped distributional bandgap in Sb 2 (S,Se) 3 solar cells is reported through a simple dual‐source vapor transport deposition process, enabling the synergetic increase of the open‐circuit voltage ( V OC ) and short‐circuit current ( J SC ). Through careful optimization, a power conversion efficiency of 7.27% under AM1.5G illumination is obtained, with V OC and J SC of 0.46 V and 29.6 mA cm −2 , respectively. This V‐shaped bandgap engineering provides an effective method to enhance the device performance and can be extended to other chalcogenide thin‐film solar cells such as Sn–X, Ge–X, Cu–Sb–X (X = S and Se), and so on.