Application of Silicon Oxide on High Efficiency Monocrystalline Silicon PERC Solar Cells

In the photovoltaic industry, an antireflection coating consisting of three SiN x layers with different refractive indexes is generally adopted to reduce the reflectance and raise the efficiency of monocrystalline silicon PERC (passivated emitter and rear cell) solar cells. However, for SiN x , a refractive index as low as about 1.40 cannot be achieved, which is the optimal value for the third layer of a triple-layer antireflection coating. Therefore, in this report the third layer is replaced by SiO x , which possesses a more appropriate refractive index of 1.46, it and can be easily integrated into the SiN x deposition process with the plasma-enhanced chemical vapor deposition (PECVD) method. Through simulation and analysis with SunSolve, three different thicknesses were selected to construct the SiO x third layer. The replacement of 15 nm SiN x with 30 nm SiO x as the third layer of antireflection coating can bring about an efficiency gain of 0.15%, which originates from the reflectance reduction and spectral response enhancement below about 550 nm wavelength. However, because the EVA encapsulation material of the solar module absorbs light in short wavelengths, the spectral response advantage of solar cells with 30 nm SiO x is partially covered up, resulting in a slightly lower cell-to-module (CTM) ratio and an output power gain of only 0.9 W for solar module.