Nanoscale structuration and optical properties of thin gold films on textured FTO

Abstract

In this work, we propose a methodology to synthesize metallic nanoparticles on textured Fluorine Tin Oxide (FTO) surface by laser irradiations of deposited Au films. In particular, the breakup of the Au films into nanoparticles (NPs) is observed as a consequence of the melting and solidification processes induced by laser irradiations. The mean Au NPs size and surface density evolution are analyzed as a function of the laser fluence. Optical characterizations of the glass/FTO/Au NPs multilayer show, in the absorption spectra, plasmonic peaks due to the Au NPs and an improvement of the light absorption efficiency from the sample with larger Au NPs. The simulated trends of the ratio between the scattering and absorption cross section suggest that the absorption efficiency dominates over the scattering efficiency in the spectral range between 200 and 600 nm. The simulation shows that, by varying the NPs radius from about 18 to 24 nm, the radiation-scattered intensity remains symmetric in forward and reverse directions. These results indicate that the surface coverage size distribution of Au NPs is the key parameter to correlate the structural and optical properties of the glass/FTO/Au NPs multilayer. Furthermore, electrical characterizations highlight a reduction in the sheet resistance of the textured FTO due to the presence of the NPs. We compare these results with those obtained for the same systems when standard furnace annealing processes are used to obtain the Au NPs on the textured FTO surface.

Experimental Analysis on the Molten-Phase Dewetting Characteristics of AuPd Alloy Films on Topographically-Structured Substrates

“…This substrate was furnished by 3SUN industry (Catania, Italy). 3SUN uses this type of substrate as a transparent conductive oxide on which commercial Si-based thin film solar cells are grown [65]. The chemical etching of the FTO layer is performed to increase its surface texturing and, so, to maximize the light diffusion within the active region of the cell.…”

“…The chemical etching of the FTO layer is performed to increase its surface texturing and, so, to maximize the light diffusion within the active region of the cell. Substrate B presents an 82.9% average transmittance in the 400-1100 nm radiation wavelength range [65]. Since substrate A and substrate B present different surface topographies (as we will show in the next section), they will serve to study the effect of the topography on the molten-state dewetting process of deposited AuPd films.…”

Metal nanostructures with complex surface morphology: The case of supported lumpy Pd and Pt nanoparticles produced by laser processing of metal films

“…[1][2][3][4][5][6][7][8][9][10][11][12]. In particular, the interest in assembling Au and Ag nanoparticles (NPs) onto conductive transparent substrates, as fluorine doped-tin-oxide (SnO 2 :F, FTO), has increased since the resulting interfaces show interesting optical properties exhibiting structure-dependent transmission/absorption spectra [13][14][15][16] due to the occurrence of localized surface plasmon resonance effects (LSPR). The effects related to LSPR are used in plasmonic solar cell to increase the energy conversion efficiency, in surface enhanced Raman spectroscopy based sensors to increase the sensitivity, in some important surface chemical reaction to increase the corresponding rate and efficiency.…”

“…Nowadays, FTO is routinely used as transparent coating for solar cell energy heat mirrors for its high electrical conductivity and high transparency at the visible and near-IR region of the electromagnetic spectrum. In the glass/FTO/metal NPs multilayer, the large fraction of radiation transmitted by the transparent layer interacts with the NPs and induces LSPR [13,14,[42][43][44] due to the collective oscillations of the NPs conduction electrons. As reported by Atwater et al [45], plasmonic nanostructures can be used as sub-wavelength scattering elements to trap the sunlight into an absorbing semiconductor film by folding the light into a thin absorber layer.…”

“…Therefore, by proper engineering of the glass/FTO/metal NPs multilayer, the light scattering into a thin semiconductor layer can be improved, then increasing the device energy conversion efficiency. In our previous works [13,14] we fabricated a prototype of Si-based thin film plasmonic solar cell by growing a p-i-n Si structure on a textured FTO/glass substrate and placing Au NPs at the p-i-n/FTO interface to exploit their plasmonic characteristics. We aimed, also, to extend our study to Pd and Pt NPs, in addition to Au NPs ones.…”