Mechanism of plasmon-mediated enhancement of photovoltaic efficiency

W Jacak (1) , J Krasnyj (1) , J Jacak (1) , W Donderowicz (1) , L Jacak (1)

1 Institute of Physics

Metallic nanospheres (Au, Ag, Cu) deposited on PV-active semiconductor surface can act as light converters, collecting energy of incident photons in plasmon oscillations. This energy can be next transferred to semiconductor substrate via a near-field channel, in a more efficient manner in comparison to the direct photo-effect. We explain this enhancement by inclusion of indirect inter-band transitions in semiconductor layer due to the near-field coupling with plasmon radiation in nanoscale of the metallic components, where the momentum is not conserved as the system is not translationally invariant. The model of the nano-sphere plasmons is developed (RPA, analytical version, adjusted to description of large metallic clusters, with radius of 10 − 60 nm) including surface and volume modes. Damping of plasmons is analyzed via Lorentz friction, and irradiation losses in far- and near-field regimes. Resulting resonance shifts are verified experimentally for Au and Ag colloidal water solutions with respect to particle size. Probability of the electron interband transition (within the Fermi golden rule) in substrate semiconductor induced by coupling to plasmons in near-field regime turns out to be significantly larger than for coupling of electrons to planarwave photons. This is of practical importance for enhancement of thin-film solar cell efficiency, both for semiconductor type (like III-V semiconductor based cells) and for Mechanism of plasmon-mediated enhancement of PV efficiency 2 conjugate-polymer-based or dye organic plastic cells, intensively developed at present. We have described also a non-dissipative collective mode of surface plasmons in a chain of near-field-coupled metallic nanospheres, for particular size, separation parameters and wave-lengths. This would find an application in sub-diffraction electro-photonic circuit arrangement and for possible energy transport in solar cells, in particular in organic materials with low mobility of carriers.

Mots clés: 73.21.-b; 36.40.Gk; 73.20.Mf; 78.67.Bf

W Jacak, J Krasnyj, J Jacak, W Donderowicz, L Jacak. Mechanism of plasmon-mediated enhancement of photovoltaic efficiency. Journal of Physics D: Applied Physics, 2011, 44 (5), pp.55301. ⟨10.1088/0022-3727/44/5/055301⟩. ⟨hal-00591293⟩