First-principles investigation of the structural, dynamical and dielectric properties of kesterite, stannite and PMCA phases of Cu2ZnSnS4

TL;DR

This study uses density functional perturbation theory to analyze the structural, dynamical, and dielectric properties of three main phases of Cu2ZnSnS4, aiming to understand discrepancies in photovoltaic efficiency.

Contribution

It provides a detailed first-principles comparison of the phases of CZTS and highlights the importance of cation disorder and defects in explaining experimental spectra.

Findings

Qualitative agreement of Raman spectra with experiments

None of the pure phases match experimental spectra within error margins

Cation disorder and defects are crucial for accurate modeling

Abstract

Cu2ZnSnS4 (CZTS) is a promising material as an absorber in photovoltaic applications. The measured efficiency, however, is far from the theoretically predicted value for the known CZTS phases. To improve the understanding of this discrepancy we investigate the structural, dynamical, and dielectric of the three main phases of CZTS (kesterite, stannite, and PMCA) using density functional perturbation theory (DFPT). The effect of the exchange-correlation functional on the computed properties is analyzed. A qualitative agreement of the theoretical Raman spectrum with measurements is observed. However, none of the phases correspond to the experimental spectrum within the error bar that is usually to be expected for DFPT. This corroborates the need to consider cation disorder and other lattice defects extensively in this material.