Enhanced absorption in nanocrystalline silicon thin film solar cells using surface plasmon polaritons

The surface plasmon polariton (SPP) is a novel approach for light trapping in solar cells. SPP enhanced nanocrystalline silicon thin film solar cells were studied in this work. Based on Mie's theory, the optical properties of Ag, Al, Cu, and Au nanoparticles were investigated approximately. The results show that the normalized scattering efficiency, scattering fraction and resonance frequency of SPP can be tuned effectively by dielectric environment, particle size and metal material. The bandgap of nanocrystalline silicon thin film were calculated based on the quantum confinement effect. To enhance the light absorption of solar cells, the resonance wavelength should be on the edge of the bandgap of absorbers, according to which the optimized matches of SPP mode and silicon grain size were discussed. As an example, 20 nm Cu particles can be used in nanocrystalline silicon solar cells which contain 5.7 nm silicon grains.