Which method is more efficient on enhancing light absorption for silicon nanowires array based solar cells: Plasmonic metal nanoparticles or narrow-bandgap semiconductor quantum dots?

Being the unique physical structure and excellent optoelectronic properties, silicon nanowires (Si-NWs) array is considered to be a key nanostructure to build low-cost and high-efficiency solar cells, showing excellent performance of photons capturing and anti-reflection. In this work, the light absorption enhancement of Si-NWs array based solar cells by filling plasmonic metal nanoparticles (NPs), such as Au, Ag and Al, and/or PbS quantum dots (QDs) in the gaps of Si-NWs or depositing on the tips of Si-NWs, are simulated by using finite-difference time-domain (FDTD) software, respectively. Based on the proposed geometry of periodic Si-NWs array, our simulation demonstrates that the light absorption in the long-wavelength region can be greatly enhanced by filling suitable metal NPs or PbS QDs to form a certain thickness layer or depositing metal NPs on the tips of Si-NWs, by making good use of the localized surface plasmons and scattering generated around metal NPs, or the high absorption of PbS QDs in near-infrared region. Also, our simulation is in agreement with experimental data reported in literatures. Therefore, our work provides a valuable theoretical basis for designing high-performance Si-NWs array based solar cells.