Excimer emission of anthracene, perylene, coronene and pyrene microcrystals dispersed in water

Luminescent Polymer Films from Simple Processing of Coronene and Europium Precursors in Water

“…The photoluminescence quantum yield for CS-PVA was measured in the concentration range 0.3 to 6 mM of CS in the precursor solution, rising to a maximum of 43% for the lowest concentration (Table S1 †). Emission from concentrations below this was too weak for accurate measurement and the higher concentrations may be adversely affected by aggregation of CS, 28 which can lead to emission quenching. 29 Values around 65% for coronene films sublimed onto glass plates have been reported in the literature, 30 whereas spincoated films in PMMA from highly-diluted solutions of coronene gave instead PLQY of about 20%, 31 which is in the range found here for PVA films, although significantly lower than our highest values.…”

Growth mechanism and size effect on fluorescence properties of perylene nanocrystals

“…5, the fluorescence spectra of perylene nanocrystals grown on Si, those on a PTCDA buffer layer, and PTCDA alone on Si are shown in red, blue, and yellow, respectively. We expected that light emissions from both self-trapped excitons (STEs) and free excitons (FEs) would be present because the size of these crystals is small enough to show a lattice softening that causes an energy relaxation through FE [4,8] in addition to STEs. On the contrary, perylene nanocrystals grown directly on the Si substrate gave only STE light emission (red spectrum), the wavelength of which ranged from 530 nm to 660 nm.…”

“…1(c), dual molecules with a face-to-face configuration occupy one lattice point, making it easy to form an excimer in the excited state. A self-trapped exciton consists of these dual molecules, similar to an excimer [4,8,16]. Light emission from STEs (hν ST E ) is dominant in the nanocrystals on Si, since the lattice distortion caused by interacting with the Si substrate makes it possible to reach the lattice relaxation energy.…”

“…Organic materials demonstrate various optoelectronic functions that depend their dimensions, including single-molecule [1][2][3], nanocrystal [4] and thin films [5,6]. In many cases, the growth mechanism and properties of organic nanocrystals have been investigated only in liquid dispersions [7][8][9] or as cast films on solid surfaces [4]. However, the growth of organic nanocrystals directly on solid substrates needs to be examined to identify properties related to size effects and to gain an understanding of the chief effects on the growth mechanism of the nanocrystal-substrate interaction.…”

Oxidation of o-chloro and o-hydroxy benzyl alcohols catalyzed by copper (II) tetraphenylporphyrin nanoparticles synthesized by mixed solvent method

“…In recent years, studies on organic nanoparticles (NPs) such as dyes and porphyrin compounds have attracted more attentions toward this area [1][2][3][4][5][6][7] . The preparation and characterization of steady nano organic compounds (NPs) with low molecular weight have not been reported yet.…”