Optimization of light trapping in polycrystalline silicon thin film solar cells using two-layer nanoparticle structure

Metal nanoparticles have been investigated as an efficient method to enhance the light absorption in thin film solar cell due to the surface plasmonic scattering. In this paper, we studied the light trapping by modifying the common silicon-nanoparticle-dielectric-back reflector structure. We reported the short circuit current (Jsc) enhancement of a two-layer nanoparticle structure, coated with two layers of magnesium fluoride (MgF2). It shows that without the application of a back reflector, the two-layer nanoparticle structure gives higher Jsc enhancement. With a back reflector, two-layer nanoparticle gives only 33% Jsc enhancement, compared with 40% enhancement for a single-layer nanoparticle structure. The modeling results confirm the experimental trends and give the loss mechanism in the twolayer structure. Potential solutions for achieving higher enhancement were also given based on the simulation result.