Defect-Assisted Recombination in Semiconductors and Photovoltaic Device Parameters from First Principles

Area of Science:

• Materials Science
• Computational Physics
• Semiconductor Physics

Background:

• Defect-assisted Shockley-Read-Hall (SRH) recombination is a major loss mechanism in semiconductors.
• Accurate calculation of SRH recombination rates is crucial for photovoltaic device performance prediction.
• Current approximations for SRH recombination dynamics have limitations.

Purpose of the Study:

• To develop a first-principles method for calculating defect-assisted SRH recombination rates.
• To accurately model steady-state recombination dynamics under non-equilibrium conditions.
• To assess the impact of defects on photovoltaic device parameters.

Main Methods:

• Full solution of rate equations for transitions across the band gap via all defect charge states.
• First-principles calculation of radiative and nonradiative multiphonon emission transition rates.
• Application of the method to seven emergent photovoltaic semiconductors.

Main Results:

• The developed method provides accurate defect-assisted SRH recombination rates.
• Evaluated the effect of specific defects on photovoltaic device parameters.
• Demonstrated limitations of commonly used approximations for recombination dynamics.

Conclusions:

• The new method advances the understanding of defect-induced losses in photovoltaics.
• Provides a computational basis for defect-tolerant semiconductors.
• Aids in the discovery of high-performance photovoltaic materials.