ZnO/ZnSe type II core–shell nanowire array solar cell

We report the realization of a prototype solar cell based on a ZnO/ZnSe core/shell nanowire array. The ZnO/ZnSe core/shell nanowire forms a type II heterojunction that can have an effective bandgap much below that of either component. The nanowire array architecture offers strong enhancement in light absorption through increasing the junction area and light trapping. The device shows a photo-response threshold of ∼1.6 eV and a large open circuit voltage of 0.7 V. Type II optical transition at the ZnO/ZnSe interface is further confirmed by transmission, photoluminescence and time-resolved photoluminescence. This result opens up new options in selecting the absorber material for a solar cell.