Relationship between the thickness of β-FeSi2 thin film and the solar photo wavelength

The β-FeSi2 thin film has been applied in the research field of the solar cell, and the thickness of β-FeSi2 absorption layer was chosen through the experiments. However, Up to now neither the optimal thickness of β-FeSi2 absorption layer nor the relationship between the thickness of β-FeSi2 absorption layer and the solar photo wavelength has been theoretically studied. In this paper, the relationship between the thickness of the absorption layer of β-FeSi2 thin film solar cell and the solar photo wavelength is calculated and analyzed by theory. The results show that the thickness of the absorption layer of β-FeSi2 is at least 200 nm when the optical absorption efficiency of the solar energy reaches 90%, and that the optimal thickness range is from 200 nm to 250 nm, and that the optimal wavelength of the photon absorbed by β-FeSi2 thin film solar cell is from 0.46 μm–0.6 μm. Furthermore, two formulas are put forward to indicate the relationship between the thickness of the absorption layer of β-FeSi2 thin film solar cell and the solar photo wavelength. The thickness of the absorption layer of β-FeSi2 thin film solar cell increases linearly with the solar photo wavelength within the optimal photo wavelength. The formulas provide a reliable theoretical basis of determining the thickness of the β-FeSi2 thin film in the solar cell.