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. Sb2S3 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 Sb2S3 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/Sb2S3 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.