Optical properties of gold and aluminium nanoparticles for silicon solar cell applications

Abstract

The optical properties of metal nanoparticles are explored as a function of lateral size, shape, aspect-ratio and metal type. Simulations based on the discrete dipole approximation are compared with experimental measurements of arrays of metal nanoparticles fabricated by electron-beam lithography. Careful selection of experimental parameters ensures minimization of far-field and near-field coupling, and inhomogeneous broadening, thus allowing comparison with single particle simulations. The optical properties of Au nanoparticles are compared with similar Al nanoparticles for each particle type. For solar cell light-trapping applications, we require metal nanoparticles that exhibit extinction peaks near the band-edge region of the absorbing material, as well as low absorption and large optical cross-sections. Al nanoparticles are shown to be of interest for amorphous silicon solar cells, but their applications for polycrystalline solar cells is limited by the presence of an interband region in the near-infrared. The opposite is found for Au nanoparticles, which feature an interband threshold region in the visible that makes their optical properties unsuitable for amorphous silicon but very suitable for crystalline and polycrystalline silicon solar cells.

Three-dimensional plasmonic stereoscopic prints in full colour

“…2c,d). These spectral shifts are consistent with the trend observed for gold/silver nanodisks that result from an increase in the dipole moment 8,29 . Electric field enhancement plots at the spectral dips for the selected pixels are shown in Fig.…”

“…2c,d), consistent with the trends observed for gold/silver nanodisks 8,29 , and with decreasing gap widths g for the nanosquares (Fig. 3c,d) 31 .…”

“…As the size of the nanostructure increases, retardation effects cause a redshift in the resonance. The increase in the extinction cross-section or oscillator strength then gives rise to the larger dip in the spectra owing to the larger dipole moment induced by the increased dimension 8,29 . E/E inc.…”

Integration of Light Trapping Silver Nanostructures in Hydrogenated Microcrystalline Silicon Solar Cells by Transfer Printing

“…However, it should be pointed out that the metal nanostructures fabricated by these approaches are usually challenging to match to the theoretical models. In contrast, the traditional nanofabrication techniques in semiconductor industries, such as photolithography and electron beam lithography, 12,13 can control structures well below the sub-100 nm level, but they are often too expensive and time-consuming to apply to solar cells, where large-area capability with low cost is essential. In order to fulfill the low-cost, high-throughput, and large-area requirements with nanoscale controllability, methods such as nanoimprint lithography, [14][15][16] …”

“…[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] These include, for instance, simple (low-cost) thermal annealing of metal films 8,9 or dispersion of pre-synthesized metal nanoparticles, 10,11 both of which resulted in successful demonstrations of plasmonic light trapping. However, it should be pointed out that the metal nanostructures fabricated by these approaches are usually challenging to match to the theoretical models.…”