Strain Tuning via Larger Cation and Anion Codoping for Efficient and Stable Antimony-Based Solar Cells

Area of Science:

• Materials Science
• Photovoltaics
• Semiconductor Physics

Background:

• Lattice distortion in antimony chalcogenides (Sb-Chs) increases defect densities, hindering photovoltaic performance.
• Self-trapping of photoexcited carriers due to Sb2S3 lattice distortion limits power conversion efficiencies (PCEs).
• Strain behavior in Sb-Chs solar cells remains largely unexplored.

Purpose of the Study:

• To investigate strain tuning in Sb-Chs by codoping with larger Bi and I ions.
• To understand the impact of codoping on lattice strain, bandgap, and defect states.
• To improve the PCE and stability of Sb-Chs-based solar cells.

Main Methods:

• Fabrication of Bi/I codoped Sb2S3 solar cells using a specific hole-transporting layer.
• Simultaneous replacement of Sb and S with Bi and I ions to induce strain.
• Characterization of strain, bandgap, trap states, and photovoltaic performance.

Main Results:

• Codoping induced significant tension and reduced compression strain in the Sb-Chs lattice.
• Bi/I codoping reduced the bandgap and passivated trap states, lowering trap state energy levels.
• The optimized 2.5 mol% BiI3 doped Sb2(SxSe1-x)3 solar cell achieved a 7.05% PCE with enhanced stability.

Conclusions:

• Strain tuning via Bi/I codoping is an effective strategy to enhance Sb-Chs solar cell performance.
• Codoping successfully passivates trap states and improves material stability.
• This approach offers a promising route for developing stable and efficient lead-free solar cells.