On energy transfer in metallically nanomodified photocells via surface plasmons in metallic nanoparticles: inclusion of nanoparticle size-effect

The energy transfer from plasmons in metallic nano-sphere deposited on the semiconductor surface to substrate electron band-system is investigated upon the scheme of Fermi golden rule. The analysis of PV efficiency dependence with respect to the nano-sphere size for plasmon mediated channel is presented for the case of photo-diode system with metallic nano-components deposited on the photo-active surface. The trade off between PV efficiency enhancement accompanying surface plasmon dipole magnitude increase with the nano-sphere size growth versus lowering tendency due to quenching of indirect inter-band transitions in substrate semiconductor, significant for smaller radii, is demonstrated in an analytical way. Plasmons in metallic nano-sphere are described within the semiclassical random phase approximation (RPA) framework, sufficiently accurate for large nanoparticles, with radius a ∼ 5 − 60 nm (for Au or Ag). Irradiation induced plasmon damping is analyzed via the Lorentz friction mechanism. The comparison with the experimental data is given supporting the formulated explanation of giant PV efficiency increase due to plasmon effect.