Research Progress of Photonic Crystal Solar Cells

Photonic crystals have been widely used in solar cells in recent years, owing to the characteristic photonic bandgap, slow photon effect and a series of unique light control performance. The introduction of photonic crystals can greatly optimize the propagation and distribution of light in solar cells. Photonic crystals can improve the performance of solar cells from five aspects: (1) Photonic crystals constructed as back mirrors to reduce light loss and increase absorption efficiency of solar cell. (2) The interaction between photons and sensitizers can be enhanced by the slow photon effect of the photonic crystal band gap, which enhances the excitation efficiency. (3) Photonic crystal can be used as a scattering layer, increasing the propagation path of light in the material, forming a resonance enhancement mode in the absorption layer, and improving the light absorption efficiency. (4) Photonic crystals have large specific surface area. Especially three-dimensional photonic crystals can provide excellent carrier for sensitizer, which can effectively increase the load and activity of sensitized molecules and improve the photoelectric conversion efficiency (5) Photonic crystals can be used to reduce the dependence of solar cells on the incident angle of sunlight. For example, when the incident light is tilted, the blue shift of the Bragg position results in more overlap with the dye absorption peak, generating a higher efficiency that partially compensates the reduced photon flux due to light inclination. However, photonic crystals in different locations of the solar cell will improve or inhibit photoelectric conversion efficiency. Therefore, the fully understanding of light manipulation of photonic crystals and their correctly application is the key to improve the photoelectric conversion efficiency. Here, the applications of different types of photonic crystals in silicon solar cells and sensitized solar cells are summarized, at the same time the possible problems are also analyzed and reviewed.