One-atom-thick sheets of germanium and tin have shown potential as semiconductors and a topological insulators respectively, and now ultrathin layers of tungsten and selenium have been used to create a diode that could be used in ultrathin, flexible, semi-transparent solar cells.

Although graphene-based solar cells have graced our pages in the past, the electronic states in graphene are "not very practical for creating photovoltaics," according to Thomas Mueller from the Vienna University of Technology. That's why he and his team went looking elsewhere and sandwiched a layer of tungsten atoms between two layers of selenium atoms. The resulting tungsten diselenide (WSe2) monolayer was found to absorb light, similar to graphene, but was also able to use the light to generate electrical power.