Broad-band absorption enhancement in lower absorption coefficient region in CZTS solar cells with embedded aluminum nanoparticles into absorber layer

Finite-difference-time-domain (FDTD) electromagnetic calculations are performed for a CZTS solar cell with embedded 100 nm aluminum (Al) nanoparticles (NPs) in the absorber layer. We predict significantly enhanced absorption for wavelengths where absorption is intrinsically low. Overall, over 17% enhancement is predicted in absorbed photon flux and (maximum attainable) current density below the absorber band gap. These are due to near-field enhancement by localized surface plasmon resonance (LSPR) and far-field enhancement by scattering from Al NPs. The increase in absorbed photon flux is explained through Mie scattering calculations in Lumerical FDTD.