Synthesis and photophysical properties of pyrene-functionalized nano-SiO2 hybrids in solutions and doped-PMMA thin films

Abstract

Luminescent pyrene-functionalized nano-SiO 2 (nano-SiO 2 Pyr) hybrids were synthesized and characterized using thermogravimetry, infrared, UV-vis absorption and, X-ray photoelectron spectroscopy, as well as field emission transmission electron microscopy (FETEM). The organic substituents immobilized on the nano-SiO 2 Pyr hybrids accounted for approximately 10% of the total weight. Polyethylene glycol 200 (PEG200) was found to be the most suitable solvent to suspend the nano-SiO 2 Pyr hybrids compared to other commonly used organic solvents. FETEM images indicated an average SiO 2 nanoparticle diameter of approximately 12 nm and a 1-to 2-nm thick organic species functionalization layer. Several emission peaks were recorded at wavelengths of 380-580 nm and were designated as emissions arising from either the monomer or excimer of the pyrene substituents. Excimer formation was concentration and solvent polarity dependent, with higher concentrations and a stronger solvent polarity benefiting excimer formation. Further, nano-SiO 2 Pyr hybrids were doped in poly(methyl methacrylate) (PMMA) thin films; fluorescence spectra indicated that the excimer could be formed almost exclusively from neighboring nano-SiO 2 Pyr hybrids. Time-resolved fluorescence decays revealed that the emission lifetimes of nano-SiO 2 Pyr monomers

Titanium Dioxide Thin Films Produced on FTO Substrate Using the Sol–Gel Process: The Effect of the Dispersant on Optical, Surface and Electrochemical Features

“…The following relationships were also used to calculate the lattice strain (ε) [47] and dislocation density (δ) [48]:…”

Unconventional Enhancement of UV Photodetection in Surface-Passivated TiO2 Thin Film Photodetectors

“…In the pursuit of efficient and cost-effective alternatives to single- or multicrystalline silicon-based devices, wide band gap semiconductor-based UV photodetectors have acquired significant attention. Semiconductors like TiO 2 , Fe 2 O 3 , Al 2 O 3 , Cu 2 O, and ZnO have emerged as promising candidates in this regard. ,− TiO 2 , in particular, stands out due to its exceptional visible transparency, robust mechanical properties, and chemical stability in aqueous solutions . This unique combination of physical, chemical, and optical properties has led to its utilization in various applications, including solar cells, gas sensors, photocatalysis, batteries, and UV detectors. − During the synthesis of TiO 2 thin films, the introduction of oxygen vacancies (O V 2+ ) throughout the film, especially at the nanoscale surface, can impede its photoresponse.…”

Dependence of the Physical Properties of Titanium Dioxide (TiO2) Thin Films Grown by Sol-Gel (Spin-Coating) Process on Thickness

“…1 Therefore, many research works were devoted to the study and synthesis different physical and chemical properties of these materials such as In 2 O 3 , TiO 2 , SiO 2 , ZnO and Bi 2 O 3 etc. [2][3][4][5] Titanium di-oxide (TiO 2 )is an important group II-VI semiconductor materials both in industry and in science fields because of its flexible properties that include a high refractive index, a large band gap (3.2 eV), high physical and chemical stability and non-toxic nature. 6,7 In addition, titanium dioxide has been extensively investigated nano-materials due to their great potential application in this field: photo-catalysis, 8 photonic device and solar cell, 9,10 optical filters, anti-reflection coatings, 11 ferroelectric and gas sensing.…”