Synthesis, photophysical and photoelectrical properties of glass-forming phenothiazinyl- and carbazolyl-substituted ethylenes

Phenothiazinyl- and carbazolyl-substituted ethylenes have been synthesized and found to constitute electro-active materials with high thermal stability as characterised by thermo-gravimetric analysis. Steady state absorption and luminescence spectra of the synthesized derivatives were examined in detail revealing green-blue emission with efficiency ranging from 13 % to 28 %. Based on the emission spectra of the synthesized compounds Commission Internationale d’Eclairage (CIE) chromaticity coordinates have been obtained. Major luminescence decay time component of ~2.5 ns was determined in dilute solutions of the compounds, whereas significantly shorter one has been estimated in thin films. Electron photoemission spectra of the materials have been recorded and the ionisation potentials of 5.3-5.4 eV have been established. Room temperature hole drift mobilities of the diarylethylenes dispersed in polymeric host approached 10-5 cm2/Vs at high electric fields

Star-shaped triphenylamine-based molecular glass for solid state dye sensitized solar cell application

International audienceThe synthesis by Suzuki cross-coupling and properties of a glass-forming star-shaped compound tris(9-(3-methylphenyl)carbazol-3-yl)-triphenylamine are reported. The thermal, optical, photoelectrical and electrochemical properties of the hole-transporting compound were studied by differencial scanning calorimetry, thermogravimetric analysis, UV/vis spectroscopy, electron photoemission, time-of-flight technique and cyclic voltammetry. The compound exhibits high thermal stability with a the temperature of the onset of the thermal degradation of 510 °C. The compound absorbs in 200-400 nm range and possesses an optical band gap of 3.15 eV, avoiding any screening effect with the dye. The solid state ionization potential (IPss) of the molecule, measured by electron photoemission and cyclic voltammetry is around 5 eV similar to the standard spiroOMeTAD hole-transporting material. The hole drift mobility in the amorphous layer of reported compound reach 6.4 × 10−5 cm2/Vs under high electrical field (6.4 × 105 V/cm). This synthesized derivative was finally assessed as hole transporting material in the solid state dye-senstized solar cells with (5-(1,2,3,3a,4,8b-hexahydro-4-[4-(2,2-diphenylvinyl)phenyl]-cyclopeanta[b]indole-7-ylmethylene)-4-oxo-2-thioxo-thiazolidin-3-yl)acetic acid (D102) as sensitizer and showed a power conversion efficiency of 0.63% under standard solar irradiation (100 mW/cm2, AM1.5