The field of plasmonics is developing rapidly and has emerged as a new area for materials and device research. Surface plasmons refer to the collective excitations of conduction electrons at the interface between a metal and a dielectric, resulting in strong field localization. By proper engineering of these nanostructures, light can be concentrated and scattered into the photoactive layer, thereby enhancing the optical absorption of solar cells. The metallic nanostructures can act as an antenna that converts incident energy from sunlight to localized surface plasmon modes. Experimentally, enhanced PCEs have been demonstrated for organic solar cells doped with silver nanoparticles due to associated plasmonic near-field effects. This unique optical property of nanometallic structures can be exploited to confine light at subwavelength scales. The excellent light trapping is critical to improve light absorption efficiency in nanoscale photovoltaic devices. 
We apply a multiscale quantum mechanics/electromagnetics (QM/EM) method to model the current-voltage characteristics and optical properties of plasmonic nanowire-based solar cells.[2-3] The QM/EM method features a combination of first-principles quantum mechanical treatment of the photoactive component and classical description of electromagnetic environment. The coupled optical-electrical QM/EM simulations demonstrate a dramatic enhancement for power conversion efficiency of nanowire solar cells due to the surface plasmon effect of nanometallic structures. The improvement is attributed to the enhanced scattering of light into the photoactive layer. We further investigate the optimal configuration of the nanostructured solar cell. Our QM/EM simulation result demonstrates that a further increase of internal quantum efficiency can be achieved by scattering light into the n-doped region of the device.
Fig. 1. Schematic diagram of a plasmonic photovoltaic device for a coupled optical-electrical QM/EM simulation. The system contains a silver nanosphere and is placed above a silicon nanowire.
For more information, please see the paper: “Multiscale Modeling of Plasmon-Enhanced Power Conversion Efficiency in Nanostructured Solar Cells”, J. Phys. Chem. Lett. 6, 4410 (2015).
Fig. 2. J-V characteristics of SiNW solar cell illuminated by the monochromatic light of frequency 3.4 eV. Black line: without nanosphere. Red line: with nanosphere at d = 0 nm. Blue line: with nanosphere and d = −7 nm. Green line: with nanosphere at d = 3 nm.
This research was supported by NSFC and National Basic Research Program of China.
. H. A. Atwater and A. Polman, Nat. Mater. 9, 205, (2010).
. C.Y. Yam, L.Y. Meng, Y. Zhang and G.H. Chen, Chem. Soc. Rev. 44, 1763 (2015).
. Y. Zhang, L.Y. Meng, C. Y. Yam, G.H. Chen, J. Phys. Chem. Lett. 5, 1272 (2014).