Phenylethenyl‐Substituted Triphenylamines: Efficient, Easily Obtainable, and Inexpensive Hole‐Transporting Materials

Malinauskas, Tadas; Daškevičienė, Marytė; Bubniene, Giedrė; Petrikyte, Ieva; Raišys, Steponas; Kazlauskas, Karolis; Gaidelis, Valentas; Jankauskas, Vygintas; Maldžius, Robertas; Juršėnas, Saulius; Getautis, Vytautas

doi:10.1002/chem.201204064

Cited by 28 publications

(35 citation statements)

References 51 publications

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“…4 During the last years, much attention has been paid to derivatives of triphenylamine because of their good holetransporting properties, making these materials promising candidates for optoelectronic and electronic devices. [6][7][8] However, recent studies [8][9][10] have reported on methoxy substituted compounds exhibiting larger hole-mobilities as compared to the nonsubstituted ones. We focus here on the influence of methoxy-and methyl substituents.…”

Section: Introductionmentioning

confidence: 99%

Can hydrogen bonds improve the hole-mobility in amorphous organic semiconductors? Experimental and theoretical insights

et al. 2015

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Five hole-transporting triphenylamine derivatives containing methoxy and methyl groups are synthesized and investigated. The hole-mobility increases in the presence of methyl-and methoxy substituents, exceeding 10 -2 cm 2 /Vs in the case of the methyl groups. Quantum mechanical calculations on these compounds indicate very different dipole moments and intermolecular interaction strengths, with intriguing correlations to the trend in hole-mobility. Temperature dependent hole-mobility measurements indicate disorder dominated hole transport. The values of the energetic disorder parameter (σ) decrease upon methyl and methoxy substitutions despite the increase in dipole moments. This trend is discussed as a function of the interaction energy between adjacent molecules, the dipole moment, the molecular polarizability, and the conformational degree of freedom. Our results indicate that the global decrease of σ upon methyl and methoxy substitutions is dominated by the the larger decrease in the geometrical randomness component of the energetic disorder. A direct correlation is established between the decrease in geometrical randomness and the increase in intermolecular interaction energies, mainly stemming from the additional C-H….π,O,N hydrogen bonds induced by methyl and methoxy groups. the dipolar-moments on the energetic disorder, 6,7 methoxy substitutions are then expected to result in degraded-or improved charge transport properties, partly depending on the (respectively) important-or negligible increase of the molecular dipole moments. As will be shown in this study, the

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Section: Introductionmentioning

confidence: 99%

Can hydrogen bonds improve the hole-mobility in amorphous organic semiconductors? Experimental and theoretical insights

et al. 2015

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“…It is worth noting that increasing compound concentration up to 10 wt % (for benzofluorenes) or 20 wt % (for fluorenes) had negligible influence on the U F and s, whereas further increase of the concentration up to 100 wt % resulted in roughly 2-fold drop of these values. Only 2-fold reduction of U F and s in the neat films is caused by enhanced nonradiative relaxation induced by exciton migration and infers rather weak emission quenching 7,16,17 and thereby weak intermolecular coupling. This was also confirmed by the small red shift of emission spectra as well as single exponential decay of the transients preserved up to the highest oligomer concentrations in PS.…”

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confidence: 87%

“…3,5 One of the main issues preventing realization of organic electrically driven laser is related to poor carrier mobility, which in the case of amorphous films may reach 0.01-1 cm 2 /V/s and 43 cm 2 /V/s in highly aligned films. [6][7][8] The low mobility induces polaron absorption, 3,9 which prevents from reaching sufficiently high current densities, and thus, threshold exciton concentrations required for stimulated transitions. Additional and no less important factor limiting concentration is exciton-exciton annihilation.…”

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confidence: 99%

Fluorene- and benzofluorene-cored oligomers as low threshold and high gain amplifying media

Kazlauskas

Kreiza

Bobrovas

et al. 2015

Applied Physics Letters

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Deliberate control of intermolecular interactions in fluorene- and benzofluorene-cored oligomers was attempted via introduction of different-length alkyl moieties to attain high emission amplification and low amplified spontaneous emission (ASE) threshold at high oligomer concentrations. Containing fluorenyl peripheral groups decorated with different-length alkyl moieties, the oligomers were found to express weak concentration quenching of emission, yet excellent carrier drift mobilities (close to 10−2 cm2/V/s) in the amorphous films. Owing to the larger radiative decay rates (>1.0 × 109 s−1) and smaller concentration quenching, fluorene-cored oligomers exhibited down to one order of magnitude lower ASE thresholds at higher concentrations as compared to those of benzofluorene counterparts. The lowest threshold (300 W/cm2) obtained for the fluorene-cored oligomers at the concentration of 50 wt % in polymer matrix is among the lowest reported for solution-processed amorphous films in ambient conditions, what makes the oligomers promising for lasing application. Great potential in emission amplification was confirmed by high maximum net gain (77 cm−1) revealed for these compounds. Although the photostability of the oligomers was affected by photo-oxidation, it was found to be comparable to that of various organic lasing materials including some commercial laser dyes evaluated under similar excitation conditions.

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“…5). 50 The 10-fold drop of Ф F with increasing compound percentage in PS up to 100 wt % was obtained for triphenylamine derivatives 27 and also for diphenylanthracene-based compounds. The slight enlargement of Ф F could be attributed to the suppressed intramolecular torsions in the environment of increased rigidity.…”

Section: Physical Chemistry Chemical Physics Accepted Manuscriptmentioning

confidence: 97%

“…The dilute solutions of BF8, BF9 and or partly disordered media. 27,45 Therefore, bulky peripheral groups such as dihexylfluorenyl moieties in the benzofluorene BF12 and the reference BF14 should cause much less ordered, i.e, amorphous films as compared to more dense films of BF8 and BF9. The fractional intensity of the component signifies its actual contribution to the overall excited-state decay and is indicated in the brackets next to the τ value.…”

Section: Excited State Dynamicsmentioning

confidence: 99%

Concentration effects on spontaneous and amplified emission in benzo[c]fluorenes

Kazlauskas

Kreiza

Radiunas

et al. 2015

Phys. Chem. Chem. Phys.

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Deep-blue-emitting benzo[c]fluorene-cored compounds featuring twisted peripheral moieties for suppressed concentration quenching of emission were synthesized and investigated as potential materials for light amplification. This detailed study of the effect of concentration on the spontaneous and stimulated emission, excited-state lifetime and susceptibility to form aggregates obtained for different benzofluorenes, has enabled the understanding of the concentration dependence of the amplified spontaneous emission (ASE) threshold and revealed the optimal concentration for the lowest threshold. The weak concentration quenching accompanied by high fluorescence quantum yield (>40%) and radiative decay rate (>5 × 10(8) s(-1)) have enabled the attainment of the lowest ASE threshold in the neat amorphous film of benzofluorene bearing dihexylfluorenyl peripheral moieties. Aggregate formation was found to negligibly affect the emission efficiency of the benzofluorene films; however, it drastically increased ASE threshold via the enhanced scattering of directional stimulated emission, and thereby implied the necessity to utilize homogeneous glassy films as the lasing medium. Although the bulky dihexylfluorenyl groups at the periphery ensured the formation of glassy benzofluorene films with the ASE threshold as low as 900 W cm(-2) (under nanosecond excitation), they adversely affected carrier drift mobility, which implied a tradeoff between ASE and charge transport properties for the lasing materials utilized in the neat form. Such a low ASE threshold attained in air is among the lowest reported for solution-processed neat films. The low threshold and enhanced photostability of benzofluorenes against fluorene compounds in air show great potential for benzofluorene-cored molecular glasses as active media for lasing applications.

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Phenylethenyl‐Substituted Triphenylamines: Efficient, Easily Obtainable, and Inexpensive Hole‐Transporting Materials

Cited by 28 publications

References 51 publications

Can hydrogen bonds improve the hole-mobility in amorphous organic semiconductors? Experimental and theoretical insights

Can hydrogen bonds improve the hole-mobility in amorphous organic semiconductors? Experimental and theoretical insights

Fluorene- and benzofluorene-cored oligomers as low threshold and high gain amplifying media

Concentration effects on spontaneous and amplified emission in benzo[c]fluorenes

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