The Solar Cell Technology department of the Institute of Electrical Engineering, CAS has fabricated CdTe (cadmium telluride) polycrystalline thin films with the thickness of only 2 µ m on commercial energy saving glass by magnetron sputtering deposition. The process only utilizes vacuum equipment and semiconductor materials from domestic suppliers. The conversion efficiency for their CdTe solar cell achieves 12.78%, as certificated byPhotovoltaic and Wind Power Systems Quality Test Center of Chinese Academy of Sciences. CdTe is a direct semiconductor with a band gap of 1.5 eV. It is one of the best candidates for terrestrial photovoltaic application, due to its band gap matching well to solar spectrum. The maximum theoretical efficiency is about 29% under standard test condition. The absorption coefficient of CdTe is as high as 5× 105/cm, which means that a CdTe film with thickness of 1 µm is sufficient to absorb more than 99% visible light in the wavelength range less than 826 nm. Such properties requires CdTe solar cell with only 1/100 thickness of silicon solar cell, which greatly reduces the material cost. CdTe thin film solar cell has caught great attention of researchers from academia and industry, due to its relatively high conversion efficiency, low cost and high stability.
