Optically Transparent, Ultrathin Pt Films as Versatile Metal Substrates for Molecular Optoelectronics

Abstract

This contribution reports a simple, straightforward method (cool sputtering) of fabricating robust, homogeneous, conductive, and optically transparent ultrathin Pt films. Their morphological, structural, mechanical, electrical, and optical properties are reported. The morphology and structure of these Pt films are investigated by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and X‐ray diffraction. The ultrathin Pt films, approximately 20 nm thick, are characterized by a homogenous, polycrystalline structure, with a tendency to adopt a (111) texture upon the thermal treatment. Moreover, thermal treatment (annealing or flaming) of the as‐prepared films also substantially improves their chemical and mechanical robustness. F films behave as bulk Pt in terms of electrical resistivity and suitability as working electrodes in cyclic voltammetry experiments. Overall, the unique combination of these excellent features: homogeneity, robustness, and conductivity, in addition to the high optical transparency in the 300–800 nm range of the electromagnetic spectrum, make ultrathin Pt films appropriate for a variety of applications in the field of molecular optoelectronics. The formation of functional molecular self‐assembled monolayers (SAMs) on these transparent, conductive films allows their optical monitoring using transmission optical spectroscopy, as well as the probing of their electrical properties. The potential of such Pt films as suitable metal substrates in opto‐ and nanoelectronics is proven by representative applications, including switching of prototypical photochromic and electrochromic species in SAMs and molecule–metal junctions.

Plasmonic metal nanostructures with extremely small features: new effects, fabrication and applications

“…), acting as the adsorption center and seeds to promote the nucleation of host metals, is an effective way to obtain UTMFs with small roughness. [66][67][68] The inset SEM images (without (left) and with a Cu seed layer (right), the scale bars are 500 nm) and the plot in Fig. 5a demonstrate that after 1 nm of Cu seed layer depositing, atomically smooth and stable Ag films with 0.5 nm roughness on silica substrate were successfully fabricated.…”

“…), acting as the adsorption center and seeds to promote the nucleation of host metals, is an effective way to obtain UTMFs with small roughness. 66–68 …”

Materials for Transparent Electrodes: From Metal Oxides to Organic Alternatives

“…Silver (Ag), Gold (Au), Chromium (Cr), Nickel (Ni) and Platinum (Pt) films and metal bi-layers with the thickness of some nanometers expose both a high conductivity and a high transparency and can compete with ITO films in terms of their opto-electronic performance. [76][77][78][79] O'Connor et al [80] reported, that a photovoltaic cell with a 9 nm thick evaporated silver (Ag) electrode displayed an even slightly higher efficiency than the ITO reference cell (see Figure 6). Thin films evaporated from a Ca:Ag blend were reported to display a sheet resistance of 27 Ohm sq -1 at 93 % transmittance (FoM 190) [81] and OPV devices based on these Ca:Ag electrodes showed a higher efficiency than the ITO reference device, but underwent rapid degradation.…”

Photonics and spectroscopy in nanojunctions: a theoretical insight

“…(3), were also considered in the literature. 139 Bare PT (6) in VMP decouples light and matter degrees of freedom, i.e. each contribution is a product of two correlation functions (electron and photon), which have to be evaluated independently.…”

“…This was shown in studies considering radiation field both classically 155,157 and quantum mechanically. 193 Finally, the fact that, e.g., electron Green functions G enters expressions for both fluxes, 6 Eqs. ( 8) and ( 9), indicates inter-dependence of the fluxes and demonstrates a necessity of consistent (i.e.…”