Effects of one-dimensional photonic crystal on thin film silicon solar cells

We have designed lateral contact thin film silicon-based solar cells with and without one-dimensional photonic crystals as back surface field layer. The photonic crystal comprises a distributed Bragg reflector (DBR) for trapping the light. Simulations demonstrate that energy conversion efficiency and short circuit current ISC for c-Si solar cells with the photonic crystal structure are increased to 21.11% and 27.0 mA, respectively, from 18.33% and 22.8mA of the one without photonic crystal. In addition, the effects of DBRs consisting of different materials are investigated in our simulations. When the refractive index difference between sub-layers of the DBR is larger, the forbidden band width is broader, the reflectance of the DBR is higher, and more photons are reflected and trapped into the active region, then the absorption efficiency and the energy conversion efficiency of the solar cell are both increased. The bigger the refractive index difference of the DBR's sub-layers is, the broader the forbidden band width is. In addition, a-Si solar cells with and without DBR are also discussed.