Optical loss analysis of Sb₂S₃ and Sb₂Se₃ thin film solar cells: A Quantitative Assessment

Abstract

Optical loss either by light reflection, or light absorption in different layers of a solar cell, can significantly impact short-circuit current density. In this paper, an optical model has been developed to analyze the optical loss in thin film solar cells made of CdS/Sb2S3 or CdS/Sb2Se3 antimony chalcogenide. This model is based on optical loss from absorption in thin layers and reflection at the interfaces of glass/TCO/CdS/(Sb2S3 or Sb2Se3) only by considering the optical properties of layers (refractive index and extinction coefficient). The transmission and reflection rate of Sb2S3 or Sb2Se3 show almost a similar trend. The absorptivity and relative loss in short-circuit current density (Jsc) versus the thickness of Sb2S3 and Sb2Se3 layers was calculated for two different structures: glass/TCO/CdS/Sb2S3 and glass/TCO/CdS/Sb2Se3. The Sb2Se3 solar cell shows a slightly better conversion performance compared to Sb2S3 solar cell due to lower reflection loss. The light reflection was calculated at four interfaces. The transmission rate of light through TCO, ITO, and CdS layers was calculated to obtain an optimal thickness for these layers. TCO showed a higher transmission rate and thus is preferred in antimony solar cell structures. The variations of (Jsc) and loss for Jsc with different thicknesses of ITO (>20%) or TCO (<20%) contact layers, favoring TCO for its lower optical losses and higher Jsc (24 mA cm−2).