Phase transition behavior and defect analysis of CuSbS2 thin films for photovoltaic application prepared by hybrid inks. (August 2019)

• Record Type: Journal Article
• Authors: Banu, Shahara; Cho, Yunae; Kim, Kihwan; Ahn, Seung Kyu; Gwak, Jihye; Cho, Ara
• Is Part Of: Solar energy. Volume 188(2019)
• Page Start: 1209
• Page End: 1220
• Publication Date: 2019-08
• Subjects: CuSbS2 solar cell -- Hybrid ink -- S-flux -- Phase transition behavior -- Recombination -- Defects; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2019.07.019
• Languages: English
• ISSNs: 0038-092X

Abstract

Highlights: A pseudo-phase transition of CuSbS2 from orthorhombic to cubic was observed for excess S-flux. Role of S-flux on structural and defect properties of CuSbS2 thin films were studied. Orthorhombic CuSbS2 showed shallower defect energy levels than that of cubic structure. Therefore, orthorhombic CuSbS2 photovoltaic cells showed improved PV performances. Abstract: CuSbS2 (CAS) thin films were deposited via a non-vacuum hybrid ink method onto a Mo/soda lime glass (SLG) substrate. To fabricate the CAS films, Cu-Sb precursors were spin coated and then annealed with sulfur powder. During annealing, different amounts of sulfur powder were used to control the crystal orientation of the films. X-ray diffraction (XRD) patterns were employed to examine the crystal orientation by calculating the texture co-efficient and Lotgering factor. It was found that the S-flux amount during sulfurization was a critical parameter for controlling the crystal orientation and phase transition of the CAS structure. Originally, CAS has an orthorhombic structure; however, if the S-flux was higher than the optimum, a pseudo-phase transition from orthorhombic to cubic was observed. In addition, the electrical characteristics and defect properties were conducted for the solar cells prepared with various S-flux to understand the difference in the photovoltaic performances affected by the structural change. Admittance spectroscopy revealed that the defect levels were shallower in the CAS solar cell with an orthorhombic structure, which could have contributed to the better photovoltaic performance than that of the cubic structure. The CAS solar cell deposited with low S-flux exhibited dominant VS 2+ defects; however, for excessive S-flux, CuSb 2− became prominent.