Influence of Down-shifting Films on Solar Cells

The luminescent down-shifting (DS) process effectively generates more electron-hole pairs in the depletion zone of solar cells at short wavelength photons. The Ce-doped YAG phosphor particles of 15-20 µm are separated via conventional filtration method and mixed with different concentrations (0.3%, 0.5%, 0.8%, and 1%) in ethylene-vinyl acetate (EVA) to make luminescent DS films, which is used for packaging the polycrystalline silicon (pc-Si) solar cells. The photoluminescent intensity of YAG: Ce particles, the transmission of luminescent DS films with different concentrations, and the performance of packaged solar cells have been analyzed. Experimental results show that a higher concentration of phosphor particles in EVA raises the surface reflection, which negatively influences the solar cell’s performance. When the particles range is fixed (15-20 µm), the luminescent DS films with the mass ratio of phosphors to EVA 10:0.03 have the highest transmission. The biggest improvement in the conversion efficiency of solar cells after packaging is due to the 10:0.08 mass ratio of phosphor in EVA. This research might be helpful for the photovoltaic industry in the future.