Use of a Selenium-Telluride Alloy as a Back Interface for CdTe-Based Cells

A variable tellurium content in a selenium telluride alloy $(\mathbf{Se}_{\boldsymbol{1-}\mathbf{x}}\mathbf{Te}_{\mathbf{x}})$ was applied to thin film CdTe based photovoltaic devices as an electron-reflector layer. Comparing tellurium contents of 10%, 50%, and 70%, and varying the thickness of the layer between 15 and 30nm; led to an initial optimization of the layer. The resulting devices showed that a thicker SeTe layer would result in lower efficiencies, and a lower tellurium content (10%) performed better in terms of $\mathbf{V}_{\mathbf{o}\mathbf{c}}$ and fill factor most notably. These selenium rich devices show great initial promise, reaching efficiencies of 19.1 %.