Modelling the electronic properties of CdSeTe solar cells

Abstract

Cadmium telluride (CdTe) is an important material for photovoltaic applications because of its low cost and high efficiency. This efficiency may be increased further by alloying cadmium telluride with cadmium selenide (CdSe), to form cadmium selenium telluride (CdSeTe). Understanding the electronic and atomic structure of CdSeTe is important for understanding how to create the most efficient photovoltaic devices possible. In this study, density functional theory is used to model the behaviour of CdSeTe. An appropriate choice of functionals is developed, and these are used to analyse the properties of CdSeTe, including crystal structure, band structure, density of states, and molecular binding energies. Analysis of the results shows a good match between the predicted band gap and experimental results. The model is then used to explore the distribution of selenium within the CdSeTe, the free energy of mixing between CdTe and CdSe, and the formation energies of point defects with CdSeTe.