Light harvesting in thin-film silicon solar cells and detectors by silver nanostructures

Light harvesting is essential for high performance thin-film solar cells made of amorphous (a-Si:H) or microcrystalline silicon (μc-Si:H). In present solar cells randomly textured TCO substrates (e.g. SnO₂ or ZnO) serving as front contacts and reflective metal back contacts (e.g. Ag) are used. Recently, the use of plasmonic effects by implementation of metallic nanoparticles has become a focus to enhance the photocurrent. Depending on the size of the Ag nanostructures, the physical effects leading to an enhancement differ. For large Ag nanostructures (>; 50 nm) the light scattering provided by localised plasmonic resonances is shown to improve the light-trapping of a solar cell for wavelengths above the band gap of the absorber material. For small Ag nanoparticles (diameter <; 40 nm) a photocurrent enhancement in the sub band gap wavelength region of a-Si:H is reported. In this contribution, the progress in the research of both effects is presented. While for large Ag nanostructures improvements of light trapping in thin-film silicon solar cells was presented, the inclusion of small Ag nanoparticles in a-Si:H is promising for extending the spectral range of thin-film silicon based detectors.