Abstract
A TiO2 thin film, prepared on fluorine-doped indium tin oxide (FTO)-coated glass substrate, from commercial off-the-shelf terpinol-based paste, was used to directly adsorb Ag plasmonic nanoparticles capped with polyvinylpyrollidone (PVP) coating. The TiO2 film was sintered before the surface entrapment of Ag nanoparticles. The composite was evaluated in terms of spectroelectrochemical measurements, cyclic voltammetry as well as structural methods such as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found that the Ag nanoparticles are effectively adsorbed on the TiO2 film, while application of controlled voltages leads to a fully reversible shift of the plasmon peak from 413 nm at oxidation inducing voltages to 440 nm at reducing voltages. This phenomenon allows for the fabrication of a simple photonic switch at either or both wavelengths. The phenomenon of the plasmon shift is due to a combination of plasmon shift related to the form and dielectric environment of the nanoparticles.
Highlights
In recent years there has been significant interest in optically transparent electrodes, due to their range of applications, including solar cells, light-emitting diodes and printable electronics [1,2].Mesoporous nanocrystalline titanium dioxide (TiO2 ) films are optically transparent for wavelengths greater than 390 nm due to their wide energy band gap, at ca. 3.2 eV [3]
Mesoporous layers are most suitable for immobilizing electroactive compounds, as the surface area available for sensitization and electrochemistry can be increased by over two orders of magnitude with respect to a flat electrode, while ensuring satisfactory access to the pores [37]
The cyclic voltammetry (CV) exhibit current composite is due to oxidation/reduction of the
Summary
In recent years there has been significant interest in optically transparent electrodes, due to their range of applications, including solar cells, light-emitting diodes and printable electronics [1,2].Mesoporous (mp) nanocrystalline titanium dioxide (TiO2 ) films are optically transparent for wavelengths greater than 390 nm due to their wide energy band gap, at ca. 3.2 eV [3]. The TiO2 films comprise a rigid, porous network which is built with 10–40 nm nanocrystalline TiO2 nanoparticles These films usually exhibit pore sizes between 5 and 20 nm, sufficiently large for dye molecules [4], metal nanoparticles [5,6,7,8], biomolecules [9], gases [10], quantum dots [11,12] and perovskites [13]. Their surface area is typically much greater (by up to 1000 times) than their geometric area [9]. In addition to their optical transparency and high surface area, these films exhibit good chemical stability, excellent optoelectronic properties and electrochemical activity at potentials above their conduction band edge. TiO2 films have been utilized in many applications such as photovoltaics [4], electrochromic windows and displays [14], antireflective coatings [13,15], batteries [14,16], touch screens [17], light-emitting diodes [18], supercapacitors [15,19], photocatalysis and photoelectrochemistry [20,21,22,23] or spectroelectrochemistry [9]
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