Simulation of High Efficiency Nc-Si /uc-Si Tandem Solar Cells

In order to improve the conversion efficiency of thin film solar cells, tandem technology is used to absorb the solar spectrum. Since nano-crystalline silicon film has the characteristic of good photosensitivity, good absorption coefficient and stability under light soak, this thin film is expected to replace the amorphous silicon as the top solar cell in tandem solar cells. In this paper, the nc-Si/uc-Si tandem solar cell was optimized by simulation. The simulation results show that the band gap of the top cell has very important influence on the conversion efficiency of the tandem cell. When the band gap increases from 1.8eV to 2.1eV, the efficiency can be raised more than 3 percentage points. And the influences of the bottom cell, the tunneling junction are also discussed.