First-principles analysis of desired inherent photovoltaic functionalities of tetragonal CuAlX2 (X=O, S, Se and Te)

Abstract

Ternary AⅠBⅢC semiconductors are significant for today's electronic equipment and solar cell applications due to their intriguing properties. In this article, first-principles calculations are employed to comprehensively study the fundamental photovoltaic properties, such as the lattice thermodynamics and phonon stability, band gap, antibonding character of band-edge states, electron and hole effective masses, exciton binding energy and optical absorption coefficient of CuAlX2 (X ​= ​S, Se and Te) materials. Outcomes demonstrate that CuAlS2, CuAlSe2 and CuAlTe2 compounds have nice mechanical stability, thermodynamic and phonon stability. Compared with CuAlS2 and CuAlSe2 crystals, CuAlTe2 possesses the more appropriate band gap value, smaller binding energy, higher light absorption and utilization efficiency. Due to their high exciton binding energy and Bohr radius, CuAlS2 and CuAlSe2 are limited to solar cell absorber applications. Certainly, other properties of CuAlS2 do not meet conditions like wide band gap value, heavy carrier effective masses and low absorption coefficient. According to direct photovoltaic functionality screening, we find CuAlTe2 crystal should be a good photovoltaic absorber.