Optimization of front and backside electrodes for a-Si:H/uc-Si:H silicon thin film tandem solar cells

As an important area, silicon thin film solar technology had made tremendous progress in the past five years. Especially, the introduction and commercialization of amorphous and microcrystalline silicon tandem thin film technology has made possible the conversion efficiency in mass production over 10%. In past several years, Chint Solar (Astronergy), one of the fewer silicon thin film PV manufacturers still in active production, had carried out extensive R&D programs involving fabrication technology improvement, new products development, unique application of thin film products and the optimization of energy out in the field et al. As a critical part in the silicon thin film solar cells, the front (window) and back electrodes (backside metallization) play the key role in light management and reduction of electrical loss. This presentation will first made a comparison study on the performance of two major transparent conducting oxides (TCOs), aluminum doped zinc oxide (AZO) and boron doped zinc oxides (BZO), as front electrodes (window). Then the impact of front electrodes on the selection of backside electrodes for silicon tandem solar cell will be discussed. Overall it is concluded that AZO and BZO gives different trapping capability for different part of the solar spectrum, and front electrodes has significant impact on the selection of backside electrodes.