Study On The Light Induced Degradation Of Silicon Thin Film Solar Cells

In order to raise the popularization of silicon based alloy solar cells, the producing cost must be reduced and the stabilized conversion efficiency must be improved. Stability is one of the factors limiting silicon thin film solar cells' development. But due to the degradation influence on amorphous silicon and microcrystalline solar cells, we have to make great efforts to investigate the stability problem of them and gain high stable conversion efficiency. In this paper, we have done such work:1. The degradation of silicon thin film materials with different crystal fraction was investigated. Measurements of the light absorption coefficient (a), light or dark conductivity and the ημτ product were conducted before, during and after light soaking. The mixed phase amorphous silicon was stabler than common amorphous silicon. The microcrystalline silicon near threshold is not stable as much as highly crystallized one, but its optoelectronic property is much more suitable than the others to made microcrystalline silicon solar cell.2. Microcrystalline silicon thin film solar cells with different crystal volume fraction (Xc) intrinsic layer were used to perform light soaking experiments under different light sources. The measurements of open circuit voltage (Voc), quantum efficiency (QE), J-V parameter and Raman spectroscopy were conducted before, during and after light soaking. The degradation of microcrystalline silicon solar cells was studied. It's found that the amorphous phase exists mainly in incubative layers.3. According to the study on the stability of the top and the bottom solar cells, the condition of the stable tandem solar cells was put forward. The model of long-term performance of amorphous tandem silicon solar cells and the method to gain the parameters were investigated, then the stabilized efficiency after 20 years was calculated.