Investigations of Defect Physics and Quenching Effect for Optimizing n-type Carrier Concentration in CuWO₄...

Area of Science:

• Materials Science
• Solid State Physics
• Photocatalysis

Background:

• Antiferromagnetic (AFM) CuWO4 is a semiconductor photocatalyst with weak n-type behavior.
• The microscopic origins of its low electron concentration and methods for enhancement are not well understood.

Purpose of the Study:

• To systematically analyze the Fermi level, electron concentration (n0), and intrinsic defect concentrations in CuWO4.
• To identify strategies for enhancing n-type conductivity in CuWO4 for improved photocatalysis.

Main Methods:

• Spin-polarized density functional theory calculations.
• Thermodynamic equilibrium simulations.
• Analysis of defect formation energies and concentrations under varying chemical potentials.

Main Results:

• Cu interstitials (Cui2+), O vacancies (VO42+), and Cu vacancies (VCu2-) are identified as dominant intrinsic defects.
• Weak n-type conductivity arises from low Cui2+ and VO42+ concentrations and compensation by VCu2-.
• Donor and intrinsic defect co-doping enhances n0 only in a narrow optimized chemical potential region (OCPR).

Conclusions:

• Quenching from 800 K to 300 K broadens the OCPR by reducing VCu2- concentration, enabling higher room-temperature n0.
• This provides an experimentally accessible route to enhance n-type conductivity in CuWO4.
• Enhanced n-type conductivity in CuWO4 can significantly improve its photocatalytic performance.