Thin-Film Solar Cells of an Indium-Modified Silver Antimony Sulfide Selenide Absorber Prepared by Spray Pyrolysis

Silver antimony sulfide (AgSbS 2 ) is considered a promising photovoltaic absorber material because of its suitable bandgap, large absorption coefficient, and environmental friendliness. However, the photovoltaic performance of AgSbS 2 -based solar cells is far from expectation and the applications of AgSbS 2 are limited by the underdeveloped fabrication technology. Herein, an effective method is developed to improve the photovoltaic performance of devices by adding indium (In) into the Ag–Sb–S system followed by a selenization process. With the addition of In, the morphology uniformity and the crystallinity of the films are simultaneously improved due to the diminished defects such as pinholes and cracks, leading to a better heterojunction interface between Ag 1− x In 2 x Sb 1− x S y Se 2− y and CdS. The Hall effect measurements demonstrate that the carrier concentration of the films effectively increases to 8.16 × 10 14 cm −3 on adding In. The optical characterization suggests that In addition significantly enhances the optical absorption and broadens the absorption wavelength range. Furthermore, the conduction band offset between the absorber and the buffer layer is substantially reduced by adding In, which lessens the carrier recombination at the interface, increasing the carriers transport efficiency. The power conversion efficiency of the Ag 1− x In 2 x Sb 1− x S y Se 2− y device is largely improved from 0.74% (In/Sb = 0) to 1.98% (In/Sb = 0.47).