UV-visible absorption study of the selfassociation of non-ionic chromonic triphenylenes TP6EOnM (n = 2, 3, 4) in dilute aqueous solutions:Impact of chain length on aggregation

A series of triphenylenes with oligoethoxy chains of various length, TP6EOnM with n = 2, 3, 4, has been synthesised and purified by HPLC. The self-association of these disc-shaped molecules in dilute aqueous solutions (?10–7 to ?4 × 10–4 M) has been studied by UV-visible absorption spectroscopy. The free energy of association decreases as the length of the chains increases. As a result, for a given concentration, the average size of aggregate diminishes as the chain length increases. While the absorption properties of the monomer are identical for the three molecules, the extinction coefficients of solutions of the three triphenylenes at a given concentration are significantly different and are directly linked to the average size of the aggregates. The change of epsilon values upon aggregation could explain the trend generally observed with dyes for solar cells substituted with chains of increasing length showing increasing extinction coefficient values

Panchromatic engineering for dye-sensitized solar cells

The dye-sensitized mesoscopic solar cell has been intensively investigated as a promising photovoltaic cell. Its ecological and economical fabrication processes make it attractive and credible alternative to conventional photovoltaic systems. In contrast to the latter design, the DSC approach separates tasks of light absorption and charge transport. The primary step of light absorption is performed by a sensitizer anchored to the surface of a wide band gap semiconductor. In order to reach a high conversion efficiency, the first requirement is that the sensitizer should absorb as much as possible of the incoming sunlight. Strategies for achieving panchromatic response in dye-sensitized mesoscopic solar cells are discussed

A triphenylene-based small molecule compatibiliser using incompatible pendent chains

A novel amphiphile-like mesogen was used to compatibilise a mixture of immiscible hydrophilic and hydrophobic triphenylenes. Importantly, the amount of compatibiliser significantly impacts the morphology of the blend.</p

Recent progress in luminescent liquid crystal materials : design, properties and application for linearly polarised emission

Fluorescent and phosphorescent liquid crystalline materials are reviewed with a focus on their application in polarised OLEDs.</p

Blue and Green Phosphorescent Liquid-Crystalline Iridium Complexes with High Hole Mobility

Blue- and green-emitting cyclometalated liquid-crystalline iridium complexes are realized by using a modular strategy based on strongly mesogenic groups attached to an acetylacetonate ancillary ligand. The cyclometalated ligand dictates the photophysical properties of the materials, which are identical to those of the parent complexes. High hole mobilities, up to 0.004 cm2 V-1 s-1, were achieved after thermal annealing, while amorphous materials show hole mobilities of only approximately 10-7-10-6 cm2 V-1 s-1, similar to simple iridium complexes. The design strategy allows the facile preparation of phosphorescent liquid-crystalline complexes with fine-tuned photophysical properties

Copper(I) complexes as alternatives to iridium(III) complexes for highly efficient oxygen sensing

Cu(i) complexes outperforming Ir(iii) complexes for optical oxygen sensing are demonstrated, which creates new opportunities for low cost sensors.</p

Synthesizing methylammonium-octhylammonium lead bromide hybrid perovskite nanoparticles

Organic-Inorganic hybrid perovskite materials have attracted significant research interest in the field of photovoltaic as well as light emitting applications. Methylammonium-Octylammonium Lead Bromide (MOPbBr3) as one of the organic-inorganic hybrid perovskite materials have been synthesized through non template chemical precipitation technique. This technique is simple and allows low cost solution processing in low temperature route to form MOPbBr3 nanoparticles. The formation of MOPbBr3 nanoparticles has been characterized through X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), X-Ray Fluorences (XRF) analyzer and Nuclear Magnetic Resonance (NMR). Exploiting the optical properties through UV-Vis spectroscopy and photoluminescence spectroscopy specifically could greatly enhance the efficiency and functionality of applications based on this materials

White-light phosphorescence emission from a single molecule: application to OLED

A simple mononuclear cyclometallated iridium(III) complex exhibits white photo- and electro- luminescence in the wavelength range from 440 to 800 nm, which originates from a single emitting excited state of mixed character.Bolink Henk, [email protected] ; Coronado Miralles, Eugenio, [email protected]

Tris-heteroleptic iridium complexes based on cyclometalated ligands with different cores

A series of tris-heteroleptic iridium complexes of the form [Ir(C^N1)(C^N2)(acac)] combining 2-phenylpyridine (ppy), 2-(2,4-difluorophenyl)pyridine (dFppy), 1-phenylpyrazole (ppz), and 1-(2,4-difluorophenyl)pyrazole (dFppz) as the C^N ligands have been synthesized and fully characterized by NMR, X-ray crystallography, UV–vis absorption and emission spectroscopy, and electrochemical methods. It is shown that “static properties” (e.g., absorption and emission spectra and redox potentials) are primarily dictated by the overall architecture of the complex, while “dynamic properties” (e.g., excited-state lifetime and radiative and nonradiative rate constants) are, in addition, sensitive to the specific positioning of the substituents. As a result, the two complexes [Ir(dFppy)(ppz)(acac)] and [Ir(ppy)(dFppz)(acac)] have the same emission maxima and redox potentials, but their radiative and nonradiative rate constants differ significantly by a factor ∼2. Then acetylacetonate (acac) was replaced by picolinate (pic), and two pairs of diastereoisomers were obtained. As expected, the use of pic as the ancillary ligand results in blue-shifted emission, stabilization of the oxidation potential, and improvement of the photoluminescence quantum yield, and only minor differences in the optoelectronic properties are found between the two diastereoisomers of each pair