Formation, migration, and clustering of point defects in CuInSe2 from first principles

Area of Science:

• Materials Science
• Solid-State Physics
• Renewable Energy

Background:

• Electronic properties of high-efficiency copper indium diselenide (CuInSe2) solar cells depend on absorber layer microstructural features.
• Controversy exists regarding the stability of point defect complexes in CuInSe2.

Purpose of the Study:

• To investigate the thermodynamic and kinetic factors behind defect complex formation in CuInSe2.
• To determine the stability and annealing behavior of specific defect complexes.

Main Methods:

• State-of-the-art calculations of defect interaction potentials.
• Analysis of activation barriers for defect complex formation and dissociation.

Main Results:

• Identified stable defect complexes including In(Cu)-2V(Cu), In(Cu)-Cu(In), and V(Se)-V(Cu).
• These complexes are stable at device operating temperatures but anneal out at higher temperatures (150-200°C for V(Cu)-related, 400°C for antisite pairs).

Conclusions:

• Defect complex formation in CuInSe2 is driven by thermodynamic and kinetic forces.
• Controlling growth temperatures allows for tuning defect complex presence and electronic activity.
• This offers a mechanism for optimizing CuInSe2 solar cell performance.