First Principles Approach to CdTe/Te Interface Band Alignment Using Density Functional Theory and Nonequilibrium Green’s Function

A computational study on band alignment of the cadmium telluride (CdTe) absorber layer and tellurium (Te) back-contact interface was performed using a first-principles approach. Inclusion of a Te back-contact on the CdTe layer establishes beneficial diode characteristics in polycrystalline CdTe-based photovoltaic devices. Density Functional Theory coupled with Nonequilibrium Green's Function was used to identify the mechanisms in Te responsible for enhancing CdTe device performance. The computational model reveals several factors that explain why Te significantly improves CdTe thin-film solar cells that include increased hole carrier concentration at the back of CdTe and mitigation of recombination at the interface.