Characterization of Sb2(S,Se)3 absorber layers fabricated by sulfurization of sb2se3 thin films

Antimony triselenide (Sb2Se3) is one of the most promising absorber material choices among the inorganic semiconductors that has attracted much attention today. However, the highest recorded efficiencies for Sb2Se3 solar cells are still lower than ideal. Exploring antimony selenosulfide (Sb2(SxSe1-x)3) to increase device performance is one option because some features of alloyed Sb2(SxSe1-x)3 depend on composition such as band gap and band position. In this study, two-step process was used to grow Sb2(SxSe1-x)3 thin films. In the first stage, Sb2Se3 thin films were deposited on soda lime glass (SLG) substrates using direct current (DC) magnetron sputtering technique. In the second stage, Sb2Se3 thin films were exposed to sulfurization process in a quartz ampoule to obtain Sb2(SxSe1-x)3 thin films. Characterization results showed that morphological, optical, and structural properties of Sb2(SxSe1-x)3 thin films grown by presented method were highly dependent on amounts of sulfur powder used during sulfurization. By the adjustment of the sulfur, Sb2(SxSe1-x)3 absorber materials with suitable band gap, favorable orientation and compact morphology can be obtained for photovoltaic applications. As discussed above, compositional manipulation of the alloyed Sb2(SxSe1-x)3 provides an opportunity to improve the ISC or VOC by simply increasing or decreasing the Se ratio in Sb2(SxSe1-x)3. In this respect, maximum efficiency can be achieved with detailed optimization. However, this approach faces a dilemma where improvement in ISC as a result of bandgap reduction is accompanied by VOC loss or vice versa. Graded solar cells can avoid this dilemma between ISC and VOC. In this study, an easy and effective method to fabricate Sb2(SxSe1-x)3 thin films with graded composition was also presented and the properties of the fabricated thin films were investigated. In order to produce Sb2(SxSe1-x)3 thin film with gradual composition, the structure fabricated by Sb2S3 thin films grown by hydrothermal deposition method on Sb2Se3 films grown by magnetron sputtering technique was subjected to heat treatment. The results of the analysis showed that the graded composition Sb2(SxSe1-x)3 thin films fabricated in our study are a potential candidate for obtaining high efficiency solar cells.