Plasmonic core-shell nanoparticle enhanced optical absorption in thin film organic solar cells

Utilizing plasmonic metal nanoparticles is considered as one of the promising methods for increasing the conversion efficiency in thin film organic solar cells. However, the bare metal nanoparticles may suffer from the energy loss introduced by themselves due to the recombination of electro-hole pairs. In this paper, the optical absorption enhancement of thin film organic solar cells with plasmonic metal-dielectric core-shell nano-particles in the active layer has been proposed and studied. It is expected that the metal core could increase the optical absorption, and consequently the conversion efficiency of thin film organic solar cells due to the localized surface plasmon based field enhancement effect, and meanwhile the dielectric shell could prevent the metal core becoming a new bulk recombination center of the light-induced excitons. Simulations are carried out by means of the finite element method in a three-dimensional model. The results show that the absorption enhancement up to 110% could be obtained when the active layer thickness is 30nm. And there is a largest thickness for the active layer, below which plasmonic metal-dielectric core-shell nanoparticles are available for increasing the light absorption of thin film organic solar cells. Then, some initial experiments have been done. The Au-citrate core-shell nanoparticles synthesized by the sodium citrate reduction method are deposited on the wafer-based silicon solar cells. And the obvious photocurrent enhancement has been observed.