High-Efficiency All-Antimony Chalcogenide Tandem Solar Cells via Thermal-Evaporated CdS Interface Engineering

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Antimony sulfide (Sb₂S₃) is a promising material for top-cell absorbers in tandem solar cells (TSCs).
• Chemical bath deposition of cadmium sulfide (CdS) electron transport layers (ETLs) leads to poor crystallinity and high roughness, causing defects and hindering performance.

Purpose of the Study:

• To engineer high-performance CdS ETLs for semi-transparent Sb₂S₃ solar cells using thermal evaporation (TE).
• To investigate the impact of TE-CdS ETLs on Sb₂S₃ film properties and device performance.
• To explore the integration of these cells into four-terminal (4T) tandem solar cells.

Main Methods:

• Fabrication of CdS ETLs using thermal evaporation (TE).
• Deposition of Sb₂S₃ absorber layers on TE-CdS films.
• Characterization of film properties (crystallinity, roughness, band alignment, defects).
• Fabrication and testing of semi-transparent Sb₂S₃ solar cells and 4T TSCs.

Main Results:

• TE-CdS films exhibited superior crystallinity, reduced roughness, and enhanced purity compared to CBD-CdS.
• Sb₂S₃ films on TE-CdS showed improved crystallinity, preferential orientation, optimized band alignment, and fewer defects.
• Semi-transparent Sb₂S₃ solar cells achieved a record power conversion efficiency (PCE) of 7.46%.
• A 4T TSC composed of Sb₂S₃ and Sb₂Se₃ reached a champion PCE of 10.51%.

Conclusions:

• TE is an effective method for fabricating high-quality CdS ETLs for Sb₂S₃ solar cells.
• Optimized ETLs significantly improve charge transport, light management, and overall device performance.
• This work advances Sb-based solar cells and their application in efficient TSCs.