Assessing Cu₃BiS₃ for Thin-Film Photovoltaics: A Systematic DFT Study Comparing LCAO and PAW Across Multiple...

Area of Science:

• Materials Science
• Computational Physics
• Renewable Energy

Background:

• Cu₃BiS₃ (CBS) is a promising earth-abundant material for thin-film solar cells.
• Ab initio studies on CBS optoelectronic properties are limited and show discrepancies.
• Establishing a reliable computational framework is crucial for advancing CBS research.

Purpose of the Study:

• To systematically investigate the impact of DFT methodologies (LCAO, PAW) and XC functionals on CBS properties.
• To identify the most suitable computational approach for accurate prediction of CBS structural and electronic characteristics.
• To provide guidance for future theoretical studies on CBS-based photovoltaics.

Main Methods:

• Employed density functional theory (DFT) using Linear Combination of Atomic Orbitals (LCAO) and Projector Augmented Wave (PAW) methods.
• Evaluated a comprehensive set of exchange-correlation (XC) functionals: LDA, GGA, meta-GGA, and hybrid (HSE06).
• Analyzed structural parameters, bandgap, effective masses, and Fermi level position.

Main Results:

• Both LCAO and PAW predict an indirect bandgap for CBS, contradicting experimental findings.
• GGA functionals (BLYP, XLYP) provided the most experimentally consistent bandgaps; LDA and meta-GGAs underestimated it.
• PAW generally yielded more accurate lattice parameters than LCAO; PW91 and HSE06 functionals showed best agreement with experimental data.

Conclusions:

• The choice of DFT methodology and XC functional significantly impacts the predicted optoelectronic properties of CBS.
• PW91 with LCAO is recommended for structural studies of CBS defects, while BLYP/XLYP with GGA are suitable for electronic property calculations.
• Further experimental validation is needed to resolve the direct/indirect bandgap discrepancy.