Influence of Geometry of Metallic Nanoparticles on Absorption of Thin-Film Organic Solar Cells: A Critical Examination

Well-engineered light trapping designs will significantly improve power conversion efficiency of thin-film organic solar cells. Recently, metallic nanoparticles (NPs) have been widely used to concentrate sunlight in the active layer of OSCs. To critically examine the influence of geometry of metallic NPs on absorption of OSCs, the parallel finite-element method is applied to simulate the near-field multiple scattering effects in plasmonic NPs incorporated OSCs. The geometry-varied NPs including nano-cone, nano-inverted-cone, nano-cylinder, and nano-cuboid are systematically investigated. Furthermore, the absorption enhancement from the dielectric silicon NPs and perfectly reflecting NPs are also comprehensively offered. Compared to the off-plasmon resonance case, the absorption enhancement factor is higher for on-plasmon resonance case. However, the absorption of organic active material near plasmon resonance weakly contributes to exciton generation. Moreover, the height-dependent Fabry-Perot mode plays a key role in the light trapping off the plasmon resonance. Additionally, the tapered structure of the silver nano-cone, which leads to the best absorption enhancement of 3 at the wavelength of 680 nm, since it can reduce unwanted reflection loss and achieve broadband plasmonic resonance simultaneously.