Solvent effect on thermally activated delayed fluorescence by 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene

Ryoichi Ishimatsu, Shigeyuki Matsunami, Katsuyuki Shizu, Chihaya Adachi, Koji Nakano, Toshihiko Imato

Research output: Contribution to journalArticle

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Abstract

Thermally activated delayed fluorescence (TADF) is fluorescence arising from a reverse intersystem crossing (RISC) from the lowest triplet (T 1) to the singlet excited state (S1), where these states are separated by a small energy gap (ΔEst), followed by a radiative transition to the ground state (S0). Rate constants relating TADF processes in 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) were determined at four different solvent polarities (toluene, dichloromethane, ethanol, and acetonitrile). We revealed that the rate constant of RISC, kRISC, which is the most important factor for TADF, was significantly enhanced by a reduced ΔEst in more polar solvents. The smaller ΔEst was mainly attributable to a stabilization of the S1 state. This stabilization also induced a Stokes shift in fluorescence through a relatively large change of the dipole moment between S1 and S0 states (17 D). Despite of this factor, we observed a negative correlation between ΔEst and efficiency of the delayed fluorescence (pd). This was ascribed to a lower intersystem crossing rate, kISC, and increased nonradiative decay from S1, knrs, in polar solvents.

Original languageEnglish
Pages (from-to)5607-5612
Number of pages6
JournalJournal of Physical Chemistry A
Volume117
Issue number27
DOIs
Publication statusPublished - Jul 11 2013

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Fluorescence
fluorescence
Rate constants
Stabilization
stabilization
Methylene Chloride
Dipole moment
Toluene
Electron transitions
Excited states
Ground state
acetonitrile
toluene
1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene
polarity
dipole moments
Energy gap
ethyl alcohol
Ethanol
ground state

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

Cite this

Solvent effect on thermally activated delayed fluorescence by 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene. / Ishimatsu, Ryoichi; Matsunami, Shigeyuki; Shizu, Katsuyuki; Adachi, Chihaya; Nakano, Koji; Imato, Toshihiko.

In: Journal of Physical Chemistry A, Vol. 117, No. 27, 11.07.2013, p. 5607-5612.

Research output: Contribution to journalArticle

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T1 - Solvent effect on thermally activated delayed fluorescence by 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene

AU - Ishimatsu, Ryoichi

AU - Matsunami, Shigeyuki

AU - Shizu, Katsuyuki

AU - Adachi, Chihaya

AU - Nakano, Koji

AU - Imato, Toshihiko

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