Enhanced broadband and omnidirectional performance of Cu(In,Ga)Se2 solar cells with ZnO functional nanotree arrays

An effective approach is demonstrated for enhancing photoelectric conversion of Cu(In,Ga)Se-2 (CIGS) solar cells with three-dimensional ZnO nanotree arrays. Under a simulated one-sun condition, cells with ZnO nanotree arrays enhance the short-circuit current density by 10.62%. The omnidirectional anti-reflection of CIGS solar cells with various ZnO nanostructures is also investigated. The solar-spectrum weighted reflectance is approximately less than 5% for incident angles of up to 60 degrees and for the wavelengths primarily from 400 nm to 1000 nm. This enhancement in light harvesting is attributable to the gradual refractive index profile between the ZnO nanostructures and air.