A hybrid functional study of native point defects in Cu₂SnS₃: implications for reducing carrier recombination

Area of Science:

• Materials Science
• Solid State Physics
• Renewable Energy

Background:

• Copper tin sulfide (Cu2SnS3) is an earth-abundant material with potential for solar cell applications.
• Native point defects significantly influence the electronic properties and performance of semiconductor materials.
• Understanding defect energetics is crucial for optimizing Cu2SnS3-based solar devices.

Purpose of the Study:

• Investigate the nature and impact of native point defects in Cu2SnS3.
• Determine the formation energies of defects under various conditions.
• Provide insights into defect control strategies for improved solar cell efficiency.

Main Methods:

• Utilized hybrid functional calculations for accurate electronic structure analysis.
• Employed the extended Freysoldt, Neugebauer, and Van de Walle (FNV) method for finite-size corrections.
• Performed charged supercell calculations to model defect behavior.

Main Results:

• Identified abundant deep centers under typical experimental conditions, detrimental to solar cell performance.
• Calculated defect energetics indicate that Sn-rich and S-poor conditions suppress detrimental defects.
• The findings align with and explain recent experimental observations on Cu2SnS3 defect levels.

Conclusions:

• Native point defects in Cu2SnS3 can form deep centers that limit solar cell efficiency.
• Fabrication under Sn-rich and S-poor conditions is recommended to minimize carrier recombination.
• This study offers a theoretical basis for enhancing Cu2SnS3 solar material performance.