Ultraviolet Pretreatment of Titanium Dioxide and Tin-Doped Indium Oxide Surfaces as a Promoter of the Adsorption of Organic Molecules in Dry Deposition Processes: Light Patterning of Organic Nanowires

Abstract

In this article we present the preactivation of TiO2 and ITO by UV irradiation under ambient conditions as a tool to enhance the incorporation of organic molecules on these oxides by evaporation at low pressures. The deposition of π-stacked molecules on TiO2 and ITO at controlled substrate temperature and in the presence of Ar is thoroughly followed by SEM, UV-vis, XRD, RBS, and photoluminescence spectroscopy, and the effect is exploited for the patterning formation of small-molecule organic nanowires (ONWs). X-ray photoelectron spectroscopy (XPS) in situ experiments and molecular dynamics simulations add critical information to fully elucidate the mechanism behind the increase in the number of adsorption centers for the organic molecules. Finally, the formation of hybrid organic/inorganic semiconductors is also explored as a result of the controlled vacuum sublimation of organic molecules on the open thin film microstructure of mesoporous TiO2.

Vacuum template synthesis of multifunctional nanotubes with tailored nanostructured walls

“…1i ) is carrying out using a temperature controlled PVD process that allows the growth of squared NWs and nanobelts. The organic nanowires are formed by self-assembly of small molecules (porphyrins, phthalocyanines and perylenes) on substrates of different chemical nature, including metal nanoparticles, polymers and oxide thin films 30 31 32 33 34 . Looking to the final applications of the nanotubes, we have deposited ONWs on commercial FTO substrates, ZnO thin films deposited by PECVD on FTO for the fabrication of the DSCs and SiO 2 nanocolumnar substrates fabricated by glancing angle vacuum deposition (GLAD) 31 36 37 for the photonic sensor.…”

“…Perylenediimide (2,9-dimethyl-anthra[2,1-def:6,5,10-d′e′f′]diisoquinoline-1,3,8,10-tetrone (Me-PTCDI) from Sensient Imaging Technologies, Octaethylporphyrin (OEP) and Nickel phthalocyanine (NiPc) from Aldrich were used as purchased. The PVD procedure for the supported formation of single crystal ONWs is fully described in previous refs 28 , 29 , 30 , 31 . It consist in the sublimation of organic molecules using a Knudsen cell in 0.02 mbar of Ar, at a growth rate about 0.3 Å/s with a controlled substrate temperature.…”

“…The methodology presented herein might be included in the last group of methods, with three important particularities. Firstly, the nanomaterials used as template are supported single crystalline organic nanowires (ONWs) fabricated by physical vapor deposition (PVD) of small-molecules 27 28 29 30 31 ; secondly, the metal oxide layers forming the walls of the NTs are prepared by remote plasma assisted fabrication 32 33 34 and finally, the template is easily removed by annealing of the ONWs at mild temperature. These characteristics render a full vacuum approach for the fabrication of NTs with tuneable length, hole dimensions and shapes, tailored wall composition, microstructure, porosity and structure.…”

A Full Vacuum Approach for the Fabrication of Hybrid White‐Light‐Emitting Thin Films and Wide‐Range In Situ Tunable Luminescent Microcavities

“…The white emission is obtained by incorporation of two photoluminescent small molecules, a blue (1,3,5‐triphenyl‐2‐pyrazoline TPP) and an orange (Rubrene) emitter (see chemical structure in Figure a) by physical vapor deposition (PVD) using as host a SiO 2 thin film fabricated by glancing angle vacuum deposition (GLAD). This type of films offers unique host possibilities for the incorporation of active molecules, metal nanoparticles, or quantum dots for the fabrication of photonic gas sensors, information encoding or biodetectors . In most of these applications the incorporation of the photonic or functional active component(s) requires the intervention of wet chemical processes .…”

“…SiO 2 GLAD thin films were prepared on fused silica and silicon substrates by electron evaporation at zenithal angles, α , of 70° and 80° . In the standard conditions, a typical distance of 80 cm separates the evaporation crucible and the substrate.…”