Plasmonic core-shell nanoparticle based thin film solar cells

The enhanced optical absorption in solar cells using nanoscale structure and novel physical effect has received a lot of attention in recent years. One of the promising methods is to utilize the noble metal nanoparticles with plasmonic effect for increasing the light absorption, consequently the conversion efficiency of photovoltaic devices. While the bare metal nanoparticles may suffer from the energy loss introduced by themselves due to the recombination of electro-hole pairs. Here, we propose to apply the plasmonic metal-dielectric core-shell nano-particles to improve the optical absorption efficiency of thin film solar cells. It is expected that the metal core could increase the optical absorption of thin film solar cells due to the filed enhancement effect of localized surface plasmon (LSP), and meanwhile the dielectric shell could avoid the metal core to become a new recombination center of the light-induced excitons. Further, varying the refractive index of the dielectric shell could adjust the enhancement region of LSP in a large range to cover the whole wavelength range of solar cells. 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 of thin film organic solar cells is 30nm thick. Then, some initial experiments have been done. The Au-citrate core-shell nanoparticles synthesized by the sodium citrate reduction method are deposited on the solar cells. And the obvious photocurrent enhancement has been observed.