Synthesis of copper (I) sulfide nanocrystals for photovoltaic application

Substantial effort has been placed on the implement of semiconductor nanostructures as building blocks for photovoltaic devices, such as dye-sensitized solar cells, all-inorganic donor-acceptor solar cells, and hybrid nanocrystal-polymer composite solar cells, which could offer alternative advantages compared with conventional single crystal solar cells and thin film solar cells. In a lot of cases, the semiconductor nanostructures typically possess a relatively large bandgap (>=1.7eV), leaving a considerable amount of solar energy unused. To generate photocurrent from low energy photons, low bandgap semiconductor nanostructures are highly desirable. We have developed a solution-phase synthesis approach for monodispersed hexagonal copper (I) sulfide (Cu2S) nanocrystals with a bandgap of ca. 1.2 eV. In addition, solar cells using the Cu2S nanocrystals and cadmium sulfide (CdS) nanorods on both glass and plastic substrates have been fabricated showing an initial power conversion efficiency exceeding 1.6%. These results provide a promising solution for low-cost power conversion.