Why are solar silicon wafers blue? To be precise, the solar cells are blue, and they are polycrystalline silicon solar cells, while monocrystalline silicon solar cells are generally black.

Why is it blue or black, because that color is the effect of Anti-reflected Coating. Solar panels mainly absorb photons near the green wavelength in visible light, and the solar panel is blue, which means that it reflects light of blue wavelength. Black is of course not reflective. So black is the best, by blue.

At present, there is a dye-sensitized solar cell, which refers to a cell in which a dye and an electrolyte are added between two transparent electrode substrates on a glass substrate or a plastic substrate. Using this technology, transparent batteries and batteries of various colors can be manufactured. The efficiency of this kind of battery is not high, and the price is cheaper than silicon.

PECVD is a necessary step in the cell production process. The purpose is to coat a layer of anti-reflection film (silicon nitride) on the surface of the silicon wafer to reduce light reflection. The thickness of the coating is about 80um. Due to the optical properties of the silicon nitride film Properties make the surface appear blue.