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.

Single Component Self‐Assembled Monolayers of Aromatic Azo‐Biphenyl: Influence of the Packing Tightness on the SAM Structure and Light‐Induced Molecular Movements

“…cis of single monolayers of azo-compounds is usually smaller than 0.003 and can be severely affected by surface plasmon bands (SPBs) of the metal surface. Unlike Au surfaces, Pt surfaces do not exhibit SPBs in the region 200-900 nm, [50][51][52] which was one of the major reasons to use both substrates in this investigation. The irradiation of the samples was performed ''in situ'', inside the spectrophotometer, to avoid artifacts related to the repositioning of the sample.…”

Template‐Confined Dewetting Process to Surface Nanopatterns: Fabrication, Structural Tunability, and Structure‐Related Properties

“…Nanostructures made of metals have attracted much interest because of their wide applications in many areas, such as in catalysis, [1][2][3][4] sensing, [5][6][7][8] data storage, [ 9 ] optoelectronics, [ 10 ] and biological related regions. [ 11 ] When the metallic nanostructures are arranged in an ordered array, some of their performances will be improved drastically.…”

Graphene‐Based Optically Transparent Electrodes for Spectroelectrochemistry in the UV–Vis Region

“…Optically transparent electrodes (OTEs) are valuable platforms for a broad range of applications stemming from fundamental spectroelectrochemical investigations of electron transfer mechanisms1, 2 to applied technological applications such as photovoltaics3–7 and organic light‐emitting diodes 8–10. OTEs have been prepared by several means including metal deposition11, 12 (e.g., Au, Pt), metal oxides13–16 (e.g., indium tin oxide (ITO), aluminum zinc oxide), and carbon7, 17–21 (e.g., boron‐doped diamond, pyrolyzed photoresist, carbon nanotubes, graphene) onto borosilicate glass or quartz glass substrates. Carbon OTEs offer several compelling advantages over metal and metal oxide OTEs including easy accessibility, excellent chemical inertness, high electrical conductivity, and the amenability for surface modification.…”