Having strong background in nanotechnology encompassing nanomaterials synthesis, investigation of physical properties of nanomaterials, and device fabrication using nanomaterials for practical applications, We envision building an interdisciplinary research program to not only explore novel nanomaterials which potentially have intriguing physical properties but also develop highly efficient nanodevices, especially for energy harvesting applications such as solar cells. We plan to extend our current research and explore new, high impact, areas of technology development.

The main obstacle for a wide spread of crystalline silicon photovoltaics would be high cost of crystalline Si wafers that have a typical thickness of 300μm and account for about 50% of the module costs. To make thin film cells whose thickness is less than 30um, we focus on the stress-induced lift-off process.  A special surface conditioning of the substrate facilitates the transfer of the device layer from a re-usable growth substrate to a low-cost device carrier. 

The use of silicon microwire arrays could achieve a competitive cost per watt of generated electricity. By employing microwire arrays on silicon photovoltaics, we would expect superior light absorption property by enhanced light trapping and improved carrier collection efficiency via orthogonal separation in directions between sunlight irradiation and diffusion of minority carriers. 

Device fabrication on a flat plastic substrate will break crystallinity of ITO (transparent conducting oxide) layer. ITO layer with crystal imperfections may bring significant problems in the device. In this project, we are seeking for a useful way to employ flexible substrate in the process of photovoltaic device fabrication for a highly efficient organic/inorganic hybrid flexible solar cells.

Vertical silicon nanowires take on a surprising variety of colors covering the entire visible spectrum, in marked contrast to the gray color of bulk silicon. This effect is readily observable by bright-field microscopy, or even to the naked eye. The reflection spectra of the nanowires each show a dip whose position depends on the nanowire radii.