⟨0001⟩-Preferential Growth of CdSe Nanowires on Conducting Glass: Template-Free Electrodeposition and Application in Photovoltaics

By contrast with the rich, wurztite-related, one-dimensional nanostructure of ZnO and its wide variety of applications, there only exists a few methods for the controlled and designed synthesis of one-dimensional CdSe nanostructures. Here, we describe a low-temperature and directed preparation of CdSe nanowires in a simple one-step, template-free electrochemical deposition. The preparation takes advantage of both the wurtzite structure characteristics and current-induced preferential orientation. High-resolution transmission electron microscopy (TEM) images and selected area electron diffraction (SAED) patterns clearly verify that the prepared CdSe nanowires have a single-crystal wurtzite structure and grow along the [0001] (c-axis). With the discovery of other one-dimensional CdSe nanostructures and CdS nanowires, it is anticipated that this electrochemical synthesis method can be extended to other nanostructures of CdSe and to other II-VI semiconductors and can also be developed into a systematic synthesis for nanostructured semiconductors. The average diameter of the thus prepared CdSe nanowires is larger than those synthesized by chemical vapor deposition (CVD) and solution-liquid-solid (SLS) methods. This may be an advantage in some applications, for example, as the light-harvesting material in photovoltaic cells. Organic/inorganic hybrid photovoltaic cells fabricated with CdSe nanowires and PEDOT:PSS give a good photovoltaic performance, demonstrating the attractive potential of CdSe nanowire applications in photovoltaics.