Synthesis of type II core/shell nanowires for photovoltaic application

The core/shell semiconducting nanowires based on II-VI semiconductors, involving with type II band energy alignments, are predicted to be a new kind of nanostructured materials for efficient charge separation for stable and efficient photovoltaic devices. In this talk, we report a successful synthesis of II-VI semiconducting core/shell nanowires by a relatively simple and low-cost approach. The structures and optical properties were characterized by applying a set of comprehensive techniques. A sharp interface and the epitaxial relationship between the core and shell were observed. Two excitonic absorption peaks were clearly found at respective excitonic bandgaps, indicating a good crystallinity of both the core and shell. Compared to the single component nanowires, the PL spectrum of the core/shell nanowires shows a reduction in intensity and a slight blue shift at the band edge emission of the core nanowires, which may partially arise from spatially charge separation between the core and shell. The direct growth of core/shell nanowires represents a major step toward fabricating a low-cost, high efficiency and stable solar cell.