Photoconductivity and optical properties of silicon coated by thin TiO₂ film in situ doped by Au nanoparticles

Abstract

Light trapping enhancement by plasmonic-active metal nanoparticles (NPs) is believed to be a promising approach to increase silicon-based solar cell efficiency. Therefore, we investigated TiO 2 films in situ doped by Au NPs (TiO 2 :AuNPs) deposited by spin coating on a silicon substrate. Photoconductivity and optical properties of the TiO 2 :AuNPs/Si structures were studied in comparison with those of TiO 2 /Si reference samples. We found that an introduction of the 40-50 nm diameter AuNPs into the antireflective TiO 2 layer deteriorates the antireflection properties and decreases the external yield of photogeneration of charge carriers. This is due to an increase of the layer reflection in the red-IR part of the spectrum, and due to the parasitic absorption of light by AuNPs in the blue-green part. Charge carrier recombination effect at the TiO 2 :AuNPs/Si interface is also found to decrease the external yield. We conclude that the TiO 2 :AuNPs layers could potentially be applied on the rear but not on the front side of Si solar cells.

Probing the Optical Property and Electronic Structure of TiO2Nanomaterials for Renewable Energy Applications

“…The optical properties for a given system are commonly defined by its band gap, which is the energy difference between the highest occupied (or VBM) and lowest unoccupied (or CBM) densities of states (DOSs) for the same, and this energy separation between the two states defines its sensitivity/responsivity to the solar spectrum. Our current understanding of the electronic structure of TiO 2 (as well as many other semiconductors) has been achieved as a result of both independent and combined theoretical (e.g., DOS and density functional theory calculations) and experimental (e.g., X-ray diffraction, X-ray spectroscopy, UV–vis spectroscopy, and Raman spectroscopy) studies. ,,,,− …”

Antireflective Coatings: Conventional Stacking Layers and Ultrathin Plasmonic Metasurfaces, A Mini-Review

“…The fabrication method of the aforementioned nanocomposites was co-sputtering; however, other methods such as thermal dewetting [ 144 ] (annealing) are also used for similar purposes. Many aperiodic systems are studied in the literature such as gold/silver clusters [ 145 ], gold-TiO 2 composite [ 146 ], gold-silica [ 147 ], silver-SiN x [ 148 ] and Al-SiN x [ 149 ]. However, photocurrent enhancement caused by Al nanoparticles sited atop a silicon diode are compared in periodic and aperiodic arrangement by Uhrenfeldt et al [ 150 ].…”

Mapping the plasmonic response of gold nanoparticles embedded in TiO2thin films

“…The structural and optical properties of the proposed materials have already been studied in detail, and show effects that needed to be confirmed at the individual NPs scale such as the role of NPs that are left exposed to air or the importance of the contribution of Au NPs localized at the interface between silicon and TiO 2 [9,10,13]. It is a known fact that the LSPR of metallic particles depends on the surrounding media [14,15].…”

“…A thin film of gold NPs dispersed in a TiO 2 matrix, (TiO 2 :AuNPs), brings together two properties that can be advantageous for silicon-based thin-film solar cells: the antireflective effect of TiO 2 coatings [9] and the light trapping enhancement due to the scattering of incident light by Au nanoparticles [8]. It has recently been proved that this enhancement is hardly noticed if the (TiO 2 :AuNPs) layer is used at the front face of a Si photoconductive device due to the parasitic absorption at the localized surface plasmon resonance (LSPR) wavelength [10]. An 8% enhancement over a standard antireflective coating has been achieved using an optimized plasmonic array of Ag spheroidal (200/125 nm wide/high) NPs [11].…”