Three-Dimensional Photovoltaic Devices Based on Vertically Aligned Nanowire Array

Abstract

The development and application of nanotechnology in renewable energy has opened up new ways to pursue next-generation solar cells which can deliver high efficiency at an economically viable cost [1–2]. A number of nano-photovoltaic (PV) concepts based on semiconductor nanowires have been developed or proposed in recent years, with either inorganic–organic hybrid [3–6] or all-inorganic approaches [7–11]. Among these concepts, of great importance is the use of quasi-one-dimensional nanowire/nanorod array to construct three-dimensional architectures as building blocks for solar light harvesting. For photogenerated carrier collection, the quasi-one-dimensional system structure is perhaps the optimized choice for optoelectronic devices such as solar cells and photodetectors, because it allows for maximally taking the advantages of reduced dimensionality while retaining the last and only needed conduction channel. Besides the possibility of exploring quantum effects when reaching the nanoscopic scale [9–10], even in the mesoscopic scale where the lateral size falls below the carrier diffusion length, the quasi-one-dimensional system could be superior to the bulk material, for instance, by reducing the non-radiative recombination and carrier scattering loss [12–13], through elimination of the unnecessary lateral transport and the resulting recombination loss [14–15].