Confined‐Space Selenium‐Assisted Tellurization Posttreatment Strategy for Efficient Full‐Inorganic Sb2S3 Thin‐Film Solar Cells

Antimony sulfide is a promising photovoltaic material because of its high absorption coefficient, green and earth‐abundant constituents, and suitable bandgap. Sb 2 S 3 planar solar cells from evaporation method without hole‐transport layer suffer from sulfur vacancy ( V S ) and a high back‐contact barrier. The same group anion exchange method demonstrates an efficient solution to fill V S and suppress the back‐contact barrier. However, the same group Te exchange with sulfur treatment has to implement at high temperature, which degrades the Sb 2 S 3 film quality. Herein, a confined‐space selenium‐assisted tellurization (c‐SeTe) posttreatment strategy is developed to overcome aforementioned challenges. Material characterizations make certain that most tellurium is distributed at the back and there is a weak signal in bulk. Further physical characterizations unfold the c‐SeTe role in device performance. The back Se and Te alloying can suppress the back‐contact barrier to improve the extraction efficiency. And, Se and Te codoping in bulk helps to passivate the interface and bulk defects so as to improve the CdS/Sb 2 S 3 heterojunction quality and enhance the long‐wavelength photon quantum yield. Finally, a champion power conversion efficiency of 4.95% is obtained, net 0.5% higher than the control one. The robust treatment method is expected to promote the fast development of antimony chalcogenide solar cells.