Tellurium complex polyhalides: narrow bandgap photoactive materials for electronic applications

Abstract

Complex metal halides are widely explored for photovoltaic applications. However, rather poor intrinsic and environmental stability of the commonly used halide-based absorbers causes a demand for more stable photoactive materials. In this work, we report a novel family of tellurium complex polyhalides with the composition A₂TeBr₆I₂. The crystal structure of these compounds contains [TeBr₆]²⁻ octahedra interconnected by I₂ bridge-molecules via halogen bonding. They are narrow bandgap semiconductors (E_g below 1.5 eV) that show strong photoresponse. Moreover, they are easily synthesized in one step from the aqueous solution. These facts make them promising candidates for use in solar cells and photodetectors.