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Polyether containing electronically isolated carbazolyl fragments and its model compound were synthesized and characterized. Weight–average molecular weight of the polymer was 31,500 with polydispersity index of 2.4. Both the compounds represent amorphous materials of high thermal stability with glass transition temperatures of 137 °C for polymer and of 41 °C for model compound. The derivatives were tested as host materials in green as well as blue phosphorescent OLEDs. The green device with polymeric host exhibited turn-on voltage of 3.3 V, a maximal current efficiency of 11.5 cd/A and maximum brightness of 1312 cd/m 2 . An efficient blue OLED using the model compound as host demonstrated a turn-on voltage of ca. 4.3 V, a maximum brightness of 6225 cd/m 2 , and maximum current efficiency of 23.3 cd/A at 100 cd/m 2 .

Carbazolyl and phenothiazinyl tetra substituted derivatives of pyrene, namely, 1,3,6,8-tetra(9-ethyl-9H-carbazol-3-yl) pyrene (1), 1,3,6,8-tetra(9-ethyl-9H-carbazol-2-yl) pyrene (2), 1,3,6,8-tetra(...

The synthesis and full characterization of new derivatives of indolo[3,2-b]carbazole with differently substituted phenyl groups at nitrogen atoms is reported. Comparative study on their thermal, optical electrochemical, and photoelectrical properties is presented. The synthesized compounds are electrochemically stable. Their highest occupied molecular orbital energy values range from -5.14 to -5.07 eV. The electron photoemission spectra of the films of synthesized materials revealed the ionization potentials of 5.31-5.47 eV. Hole drift mobility of the amorphous film of 5,11-bis(3-methoxyphenyl)-6-pentyl-5,11-dihydroindolo[3,2-b]carbazole exceed 10(-3) cm(2)/V·s at high electric fields, as it was established by xerographic time-of-flight technique. In contrast to diphenylamino substituted derivatives of carbazole, no effect of the position of methoxy groups on the photoelectrical properties was observed for the synthesized methoxyphenyl-substituted derivatives of indolo[3,2-b]carbazole. The indolo[3,2-b]carbazole core has a larger resonance structure that includes 3 phenyl rings, and thus the energy gap of the HOMO and LUMO π orbitals is lower as compared to that of carbazoles. With a larger energy difference between the phenyl substituents and the core moiety, the indolo[3,2-b]carbazole derivatives studied all have a weaker coupling between the phenyl group and a much weaker dependence of the molecular properties on the position of substituents on the phenyl groups as compared to those observed in substituted carbazoles.

Synthesis and thermal, optical, electrochemical and photoelectrical properties of new indazole-based electroactive materials are reported. 1-Phenyl-5(6)-[N,N-(bisphenyl)]aminoindazoles and their methoxy-substituted analogues exhibit high thermal stabilities with the onset temperatures of thermal degradation ranging from 352 to 424 °C. The synthesized indazole derivatives form glasses with glass transition temperatures ranging from 35 to 39 °C. The synthesized compounds are electrochemically stable: their cyclic voltammograms show one reversible oxidation couple and no reduction waves. The ionization potentials of the solid samples of the synthesized materials are in the range of 5.3–5.9 eV. Methoxy-substituted derivatives show lower ionization potentials. Time-of-flight hole drift mobilities of 50% solid solution of 1-(4-methoxyphenyl)-5-{N,N-[bis(4-methoxyphenyl)]}aminoindazole in bisphenol Z polycarbonate reach 10−5 cm2/V s at high electric fields.

Three glass-forming 1,3-bis(carbazol-9-yl)propan-2-ol based monomers, i.e. oxirane, thiirane and oxetane were synthesized. Photopolymerization of their solid amorphous layers initiated with diphenyliodonium tetrafluoroborate and the dark polymerization in solutions initiated with boron trifluoride etherate were performed. The number-average molecular weights of the obtained polymers are in the range of 1000–19,400. The highest initial polymerization rate, the highest limit conversion and the highest molecular weight were observed for the polymerization of thiirane. Optical, photophysical, electrochemical and thermal properties of the synthesized compounds were studied. UV and fluorescence spectra of the compounds have the similar profiles, due to the presence of the same chromophore. No excimer emission was observed neither for dilute solutions of monomers nor polymers. The electrochemical coupling was observed for all the synthesized 1,3-bis(carbazol-9-yl)propan-2-ol based monomers and polymers by cyclic voltammetry. The thermal degradation of the derivatives of 1,3-bis(carbazol-9-yl)propan-2-ol derivatives starts in the range of the temperatures from 317 to 402. The glass transition temperatures of the monomers range from 43 to 58 while glass transition temperatures of the polymers are in the range of 103–125.

Branched diphenylsilane derivatives with pendent indolyl fragments were synthesized and characterized. The compounds show high thermal stability with thermal decomposition starting at temperatures above 367 °C and ability to form glasses with glass-transition temperatures of 53–58 °C. The electron photoemission spectra of the layers of the synthesized compounds showed ionization potentials of ca. 5.85 eV. The derivatives were tested as host materials in phosphorescent OLEDs with iridium(III)[bis(4,6-difluorophenyl)-pyridinato- N , C 2′]picolinate as the guest. The device with the host derivative containing four electronically isolated indolyl fragments exhibited the best overall performance with maximum current efficiency of about 12 cd/A.

The polymerization of 2-(9-carbazolyl)methylthiirane (CMT) in the presence of cyclic oligo(potassium glycidoxide) as the macroinitiator activated 18-crown-6 leads to star-shaped polythioether with a cyclic core and mainly six arms, and with molecular masses relatively near to the calculated ones. A particularly intensive blue photoluminescence is shown by poly(CMT) in tetrahydrofuran solution at the concentration equal to 2 × 10 −6 mol/dm 3 . This polymer dispersed in commercially available transparent polymers, i.e. poly(methyl methacrylate), polycarbonate or polystyrene gives blue photoluminescent materials.

The electroluminescent device ITO/CuI/3,6-di(9-carbazolyl)-9-(2-ethylhexyl)carbazole(TCz1)/Ca/Al in which TCz1 for the first time was used as the emitting layer, was fabricated by means of vacuum deposition. The device emits blue light with a peaks at 388 and 406 nm at 4.5 V, with high current efficiency values (11.5 cd/A) and external quantum efficiency (1.72%).

Aza-compounds derivatives such as carbazole and phenothiazine are intensively studied as potential components of organic electronics, particularly of OLEDs. The present paper deals with investigations of spectral properties of specific carbazole- and phenothiazine-containing low-molecular glass-forming compounds, i.e., 3-(9-carbazolyl)-9-ethylcarbazole, 3-(9-pheothiazinyl)-9-ethylphenothiazine, 3-(9-pheothiazinyl)-9-ethylcarbazole, and 3-(9-carbazolyl)-9-ethylphenothiazine in different aggregative states (solid samples and solutions) and at different temperatures (77° K, 293° K). The location of the first singlet and triplet energy levels of the investigated compounds has been estimated from the spectral data. The high probability of the intercombinatory transition to the triplet state for the solutions and solid samples of 3-(9-pheothiazinyl)-9-ethylphenothiazine, 3-(9-pheothiazinyl)-9-ethylcarbazole, and 3-(9-carbazolyl)-9-ethylphenothiazine has been stated.

The synthesis and properties of carbazole and diphenylamine derivatives with different numbers and positions of methoxy groups in the diphenylamino moiety are reported. A comparative study on their thermal, optical, and photoelectrical properties is presented. All the synthesized compounds are found to form glasses with the glass transition temperatures in the range of 39−69 °C, as characterized by differential scanning calorimetry. The ionization potentials of the synthesized compounds were estimated both theoretically by quantum chemical calculations and experimentally by an electron photoemission in air technique. The trends observed by theoretical calculations are confirmed by experimental results. The experimental values of ionization potentials range from 5.10 to 5.56 eV. Compounds containing monomethoxy-substituted phenyl rings exhibited lower ionization potentials than compounds containing di- and trimethoxy-substituted phenyl moieties. The highest ionization potential was observed for the compoun...

Methyl methacrylate (MMA) was copolymerized with 9-anthrylmethyl methacrylate (AMA) or 2-(9-carbazolyl)ethyl methacrylate (CMA) under controlled atom transfer radical polymerization (ATRP) conditions. It yielded well-defined luminescent copolymers, which emitted light with various wavelengths and intensities depending on their compositions.

A series of new derivatives of indolo[3,2- b ]carbazole containing phenyl, fluorenyl and carbazolyl substituents at the nitrogen atoms were synthesized by Ullmann coupling of 6-pentyl-5,11-dihydroindolo[3,2- b ]carbazole with the different aryl halogenides. The optical, photophysical, photoelectrical and thermal properties of the materials obtained were studied. All the synthesized compounds can be transformed into the amorphous phase with the glass transition temperatures ranging from 0 to 154 °C. The ionization potentials of the newly synthesized derivatives of indolo[3,2- b ]carbazole are in the range of 5.22–5.48 eV. The lowest energy absorption edges and the lowest ionization potentials were observed for carbazolyl-substituted derivatives. Charge transport properties of the synthesized materials were estimated by the time-of-flight technique. The highest hole drift mobilities were observed for the fluorenyl-substituted derivative. For the molecular glass of 5,11-bis(9,9-dibutyl-9 H -fluoren-2-yl)-6-pentyl-5,11-dihydroindolo[3,2- b ]carbazole they exceed 10 −3 cm 2 /V s at an electric field of 3.6 × 10 5 V/cm.

Photostability of phenothiazinyl-substituted ethylenes in both solution and in solid state (thin films) was investigated as a function of UV exposure time. Fluorescence intensity and spectral variation measurements in the presence and absence of ambient air were used to determine the effect of oxygen on the degradation of the compounds. The observed reduction in the fluorescence efficiency of air-saturated solutions and thin films subjected to UV was attributed to permanent photo-oxidative degradation. Photostability was higher in the cases of molecules that contained two bulky phenothiazinyl groups as compared to those containing only one phenothiazinyl group and a smaller phenyl substituent. Fully reversible fluorescence intensity decay in the degassed phenothiazine solutions was attributed to photo-isomerization, whereas the partially reversible changes in fluorescence intensity that were observed for films in the absence of air were ascribed to both photoexcited carrier capture by deep-traps acting as exciton quenching centres and degradation imparted by UV-induced bond scission.

A new monomer, 3-[{(oxiran-2-yl)methoxy}methyl]-9-ethyl-9H-carbazole (OMEC), was synthesized by the reaction of 9-ethyl-3-(hydroxymethyl)carbazole with (1-chloromethyl)oxirane in the presence of KOH. Cationic photopolymerization of OMEC initiated with diphenyliodonium tetrafluoroborate (DPIB), cyclopropyldiphenylsulfonium tetrafluoroborate (CPB) and (η 5-2,4-cyclopentadien-1-yl) [(1,2,3,4,5-η)-(1-methylethyl) benzene]-iron (+)-hexafluorophosphate (–1) (Irgacure 261) was studied. The initiator exponent was established for the photopolymerization of OMEC initiated with DPIB. The influence of the temperature and oxidizing agent benzoyl peroxide on the polymerization rate and the conversion limit of OMEC photopolymerization initiated with Irgacure 261 is discussed. An activation energy value of 17 kJ/mol was estimated for OMEC when photopolymerization was initiated with Irgacure 261. Post-polymerization reactions of OMEC were studied.

New carbazole-based polymers, which contain various content of electro-active fragments in the main chain connected via alkylene spacers, have been synthesized by Ni(0)-catalyzed Yamamoto-type aryl–aryl coupling reactions. These compounds represent amorphous materials of high thermal stability with glass-transition temperatures of 139–151 °C and thermal decomposition starting at temperatures above 400 °C. UV–vis absorption and photoluminescence emission spectra of the materials confirmed that the conjugated segments in the macromolecules are rather short. However, the polymers with varying content of the electro-active chromophores demonstrate different charge injection and transport properties in multilayer light emitting diodes with the polymers as the hole transport and tris(8-quinolinato)aluminium (Alq 3 ) as the electroluminescent/electron transport layer. The device based on the polymer containing bicarbazole segments in the main chain exhibits the best overall performance (turn-on voltage: 4 V; maximum photometric efficiency: 2.6 cd/A; maximum brightness: approximately 2200 cd/m 2 ).

Charge-transporting and photoluminescent phenothiazine and carbazole adducts were synthesized and their thermal, optical, photophysical and photoelectrical properties were studied. The materials synthesized were found to constitute glasses with glass transition temperatures in the range of 63–78 °C. Their initial weight loss temperatures range from 334 to 362 °C. Steady state and time-resolved fluorescence spectrometry techniques have revealed energy transfer in the adducts of carbazole and phenothiazine and the existence of excimer forming sites in the films of 3-(10-phenothiazinyl)-9-ethylcarbazole and 3-(9-carbazolyl)-9-ethylcarbazole. The electron photoemission spectra of the materials were recorded and the ionization potentials of 5.38–5.87 eV were established. Time-of-flight hole drift mobilities of carbazole twin compound molecularly dispersed in bisphenol Z polycarbonate (1:2 by weight) approach 2 × 10 −5 cm 2 /V s at high electric field.

The synthesis and properties of hole-transporting triaryl diamine-based low-molar-mass compounds and polymer are reported. Comparative study on their thermal, optical, and photoelectrical properties is presented. All the synthesized compounds are found to form glasses with the glass transition temperatures in the range of 43–119 °C as characterized by differential scanning calorimetry. The ionization potentials of these compounds range from 5.31 to 5.40 eV as determined by electron photoemission method. Hole-drift mobilities in the films of the synthesized compounds were estimated by the xerographic time-of-flight technique. They were found to reach 10−3 cm2/Vs at electric field of 6.4 × 105 V/cm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4674–4680, 2008

A new epoxy resin derived from Meldrum acid (DGMA) was synthesized by a two steps synthetic procedure and structurally characterized by the usual spec- troscopic techniques and elemental analysis. Ytterbium and lanthanum triflates were tested as cationic initiators to cure this resin and its mixtures with diglycidylether of bisphenol A (DGEBA) in several proportions. By FTIR-ATR spectroscopy the evolu- tion of the groups, which participate in the curing was followed. The evolution of the curing and the Tg of the materials were studied by differential scanning calorimetry and the kinetic parameters were calculated applying isoconversional procedures. Ytterbium triflate led to a quicker curing than lanthanum. The thermal stability of the materials obtained was evaluated by thermogravimetry and the higher thermal degradability of the materials containing DGMA was confirmed. V

Summary of the physical properties of the carbazole monomer, oligomers,and other carbazole-based molecules. Compound T d [a][°C] T g [b][°C] k max, abs. [c][nm] k max, fluo. [d][nm] k max, phos. [e][nm] E singlet [f][eV] E triplet [g][eV]Cz – – 343 351 409 3.53 3.03BCz1 299 67 344 376 416 3.30 2.98BCz2 334 104 343 373 413 3.32 3.00BCz3 322 77 358 414 448 3.00 2.77TCz1 384 88 344 389 424 3.19 2.92TCz2 413 150 343 388 422 3.20 2.94CBP – 62 341 355 485 3.49 2.56mCP – 60 340 348 427 3.56 2.90SimCP – 101 [h] – – 427 [h] – 2.90 [h] [a] Temperature corresponding to a 5% weight loss in thermogravimetric analysis.[b] Glass-transition temperature determined by differential scanning calorimetry.[c] Absorption maximum in solutions (1×10 –5 in toluene). [d] Fluorescence peak insolutions (1×10 –5 in toluene). [e] Phosphorescence peak in solutions (1×10 in tolu-ene, 77 K). [f] Singlet energy estimated from the highest-energy fluorescence peak.[g] Triplet energy estimated from the highest-energy phosphorescence peak. [h] Prop-erties of SimCP were obtained from reference [7].

Various indolyl-substituted carbazole derivatives were synthesized and found to constitute glass-forming materials with glass transition temperatures in the range of 40–95 °C as characterised by differential scanning calorimetry. The electron photoemission spectra of the materials were recorded and the ionisation potentials of 5.2–5.7 eV were established. Time-of-flight hole drift mobility of the indolyl-substituted carbazole dihydrazone molecularly dispersed in bisphenol Z polycarbonate approached 4 × 10−6 cm2/V s at high electric field.

Various phenothiazinyl-based hydrazones including cross-linkable derivatives have been synthesized by the multi-step synthetic route. Full characterization of their structure is presented. The materials were examined by various techniques including differential scanning calorimetry, UV spectrometry, electron photoemission and time of flight techniques. The electron photoemission spectra of the layers showed the ionisation potentials of 5.3–5.4 eV. Room temperature hole drift mobility of some derivatives molecularly dispersed in bisphenol Z polycarbonate approached 5 × 10 −6 cm 2 /Vs at high electric fields.

Photopolymerization of neopentyl glycol diglycidylether (NPG) initiated with diphenyl iodonium tetrafluoroborate (TB) in bulk has been studied. The influence of concentration of the photoinitiator on the rate of polymerization and monomer conversion is discussed. The initiator exponent was established for the photopolymerization of NPG with TB. Photopolymerization of the compositions consisting of NPG and 9-(2-oxiranylmethyl) carbazole (OMC) initiated with TB has been studied. It was established that OMC undergoes both homopolymerization and copolymerization during the UV irradiation of the composition. The effect of the temperature on the rate and conversion of epoxy groups for the photopolymerization of NPG alone and in the presence of OMC has been examined. It was established that 9-vinylcarbazole (VCz) acts as synergist of NPG photopolymerization as well of photopolymerization of the composition of NPG and OMC.

We demonstrate the fabrication and properties of an near ultraviolet organic light emitting diode (UV OLED) that contains 2,7-di(9-carbazolyl)-9-(2-ethylhexyl)carbazole organic emitting layer and aluminumdoped magnesium zinc oxide (ZnMgO:Al) layer as transparent electrode. The obtained ZnMgO:Al layer is transparent for the wavelengths longer than 325 nm and has low resistivity of the order of 10−3 Ωcm. The UV OLED device turns on at the applied voltage of 9 V.

Cataloged from PDF version of article. The results of an experimental study of the electroluminescent device made of ITO/CuI/2,6-di-tert-butyl-4-(2,5-diphenyl-3,4-dihydro-2H-pyrazol-3-yl)-phenol (HPhP)/3,6-Di(9-carbazolyl)-9-(2ethylhexyl) carbazole (TCz1)/Ca:Al with efficacy up to 10.63 cd/A are presented. HPhP provides blue emission with a peak wavelength at 445 nm. The layer of TCz1 acts as an electron-transporting layer. In the framework of density functional theory (DFT) approach the geometry configuration and energy levels of HPhP are found being in a good agreement with spectral and cyclic voltammogram data. (C) 2011 Elsevier B.V. All rights reserved.

A series of perylenediimide-based small molecules (PDI1-PDI5) containing electron-deficient groups in the bay region were synthesized and characterized. The PDI derivatives were found to be capable of forming molecular glasses with glass transition temperatures ranging from 50 to 102 degrees C. Detailed investigations of the optical properties of the synthesized derivatives were performed and compared with those obtained from quantum chemical calculations. Optimized molecular structures of the PDI derivatives exhibited core-twisting by 16 degrees and torsional angle between the bay substituent and the perylene core in the range of 60-72 degrees. The PDI derivatives exhibited absorption maxima in the range of 2.27-2.36 eV and emission maxima in the range of 2.10-2.28 eV. The impact of the bay substituents on the emission, fluorescence quantum yield, and lifetimes in solutions and thin films was established. The red shift of emission maxima (from 2.282 to 2.095 eV) observed for various PDIs in solutions was accompanied by significant reduction in the emission quantum yield (from 0.73 to 0.44) and corresponding increase of the fluorescence lifetime (from 4.5 to 6.8 ns). This was in agreement with quantum chemical calculations indicating decrease of the radiative relaxation rate due to reduction of the oscillator strength and remarkable decrease of the torsional activation barrier. The spectral properties of the wet-casted perylenediimide films featuring different bay substituents were also studied. The variation in the emission peak (of 0.25 eV) and the considerable increase of the Stokes shift (of 0.4 eV) are explained in terms of the formation of the amorphous state. The influence of the bay substituents on the thermal and spectral properties of the films are discussed.

2,2-Bis{4-[2-(vinyloxy)ethoxy]phenyl}propane (BPA) monomer was synthesized and its cationic photopolymerization with triethyleneglycol divinyl-ether (DVE3) investigated. Real-time FT-IR kinetic investigations showed, in the presence of DVE3 monomer an increase of the photopolymerization rate and of the final vinyl ether double bond conversion. All the formulations investigated gave rise to transparent films characterized by a high gel content (>94%). An increase of Tg values by increasing the BPA content was observed by DSC and DMTA analyses; it was attributed to the rigid bisphenol-A-units introduced within the polymeric network. DMTA analyses showed an increase of the modulus E′ by increasing BPA content. Surface hardness of the cured films was improved by BPA copolymerization.

The synthesis of some carbazole compounds containing vinyl ether, epoxy or hydroxy groups is reported. They are used as photosensitizers in cationic photopolymerization of vinyl ether and epoxy systems. In clear coatings an increase of the rate of photopolymerization was observed, the most active compound being 1,3-di(carbazol-9-yl)propanol-2. The same behaviour was observed in photosensitized pigmented coatings containing TiO2. An increase of Tg of cured films was observed in the presence of the photosensitizer; also an increase of hardness and solvent resistance was evidenced.

This article reports the synthesis of new carbazole based polymers and their application as hosts in sky-blue polymer light emitting devices (PLEDs) with a solution-processed emitting layer doped with a cyclometalated Ir(III) complex. We systematically investigate their effect on the PLED performance. A current efficiency of 19.7 cd A−1 and a brightness of 1850 cd m−2 were achieved with these polymers. The roll-off in electrophosphorescent quantum efficiency in PLEDs was shown to arise mainly from triplet–triplet annihilation between dopants in the hosts with tert-butyl groups. It has been shown that in the devices with hosts without tert-butyl groups the efficiency roll-off is additionally affected by electric field quenching. In these carbazole based polymers, triplet dimers are formed and tert-butyl groups do not limit the intermolecular interactions to prevent triplet dimer formation, nevertheless tert-butyl groups reduce charge transport.

Study of charge carrier transport in organic electroluminescent devices, organic photovoltaic devices, and organic field-effect transistors is one of the most important points. In order to realize comparable electron and hole transport in thin organic films with electrodes the energy structure of such devices are of great importance. In this work, we have studied electrical properties and energy structure of two carbazole derivatives. The threshold energy of photoconductivity quantum efficiency is 2.90 eV and optical energy gap is 3.3 eV in thin films is obtained. The values of work function of ITO, Au, Cu and Pd electrodes are energetically close to conductivity level of holes and holes injection dominates from electrodes. In these thin films local trapping states of holes are situated at holes conducting level. When electrode is Al layer the local shallow trapping states for electrons at Et = 0.10 eV for compound 1 and at Et = 0.18 eV for compound 2 are determined.

New oxiranyl-substituted derivatives of 3,9′-bicarbazole were synthesized by synthetic route involving Ullmann coupling, Vilsmeier formylation, reduction with sodium borohydride and the interaction of hydroxymethyl derivatives with 2-(chloromethyl)oxirane. The optical, photophysical and photoelectrical properties of the newly synthesized materials were studied. The electron photoemission spectra of the materials revealed the ionization potentials ranging range from 5.55 to 5.70 eV. Time-of-flight hole drift mobilities of bisphenol Z polycarbonate doped with 50 wt.% 3,9′-bicarbazole -based compounds exceed 10−6 cm2/V · s.

Carbazole-based imines were synthesized by the reactions of 3-amino-9-ethylcarbazole with heteroaromatic aldehydes (3-formyl-9-ethylcarbazole or 3-formyl-10-(2-ethylhexyl)phenothiazine) or with 4,4′-bis(dimethylamino)benzophenone. The characterization of the derivatives synthesized by 1H NMR and IR spectroscopy as well as by MS spectrometry is presented. The electron photoemission spectra of thin layers of the materials were recorded and the ionization potentials of ca 5.3 eV were established. Hole drift mobilities in the layers of bisphenol Z polycarbonate containing 50% of the electro-active material reached 4 × 10−6 cm2/Vs at an electric field of 1.4 × 106 V/cm.