Transparent Conducting Oxides

Transparent conducting oxides (TCOs) play a crucial role in thin film solar cells.  Central to the operation of such cells is the ability to have solar radiation penetrate the cell and be absorbed, with the light efficiently converted to an electrical current that can be extracted.  To accomplish this in thin film solar cells, the outer body of the cell needs to be optically transparent yet electrically conducting.  TCOs are the enabling technology in this regard.  There is an inherent competition between optical transparency and electrical conductivity, and great efforts are being expended to achieve low resistivity TCOs that can be doped reproducibly both n-type or p-type.  Since the interest in TCOs lies in their electronic properties, a comprehensive study of their electronic structure is of vital importance in understanding the properties of these materials, improving their synthesis, and discovering new TCOs.  We are measuring the detailed surface and bulk electronic structure of novel TCOs using our set of complimentary synchrotron radiation-based soft x-ray spectroscopies.