Novel Light Trapping in Thin Film Solar Cells with Nano Particles and Integrated Diffraction Grating

To over come the lower absorption of solar radiation in thin film solar cell a novel technique of combining metallic grating and metallic nano particle is presented. The increase in absorption is associated with localized surface Plasmon’s resonance that depends on many factors ranging from the size of nano particle to its shape, material of nano particle, polarization of light and the medium of enviroment in which the solar cell is placed. The solar cell is designed in COMSOL Multiphysics environment which uses the numerical finite element method (FEM). The enhancement of absorption of spectral density in the solar radiation is demonstrated, theoretically. The collective oscillaton of the metallic nano particles and metallic grating produces individual electric field thus interacting with each other to produce higher modes of excitation. This collective mode supports the dark modes of nano partiles which is very useful for harnessing the long range of radiation. To reduce reflection from the top of solar cell, anti reflection coating is provided at the top whereas the back of solar cell is made of metallic reflector aluminium. The different simulations reveals that the antireflection coating has negligent effect on the absorption of solar cell by using the integrated structure of metallic grating and nano particles.  Moreover, this approach is suited for thin film solar cell which will absorb more radiations due to the multiple peaks in the spectrum of the aforementioned proposed structure.