Numerical Investigation of Conduction Band Offset and Back Surface Field Effects in CBTSSe Solar Cells Using SCAPS-1D

Abstract

This study presents a comprehensive numerical investigation of thin-film CBTSSe-based solar cells using SCAPS-1D, focusing on interfacial and band alignment engineering to enhance device performance. The simulation model was validated against experimental results, showing excellent agreement in photovoltaic parameters. The influence of the electron transport layer (ETL) on conduction band alignment was evaluated for CdS, TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>, and WS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>. ETLs with electron affinities between 3.95 and 4.25 eV yielded optimal offsets and minimized interface recombination. A CdTe back-surface-field (BSF) layer further enhanced carrier confinement and passivation. The optimized WS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>/CBTSSe/CdTe configuration achieved a simulated efficiency of 9.77%, representing a significant improvement over the validated baseline. These results highlight the predictive reliability of SCAPS-1D and the role of band alignment in optimizing non-toxic CBTSSe Solar Cells.