TY - JOUR
T1 - Intersystem Crossing Rate in Thermally Activated Delayed Fluorescence Emitters
AU - Kobayashi, Takashi
AU - Kawate, Daisuke
AU - Niwa, Akitsugu
AU - Nagase, Takashi
AU - Goushi, Kenichi
AU - Adachi, Chihaya
AU - Naito, Hiroyoshi
N1 - Funding Information:
This work was financially supported by JSPS KAKENHI, grant nos. JP18H03902, JP17K18993, and JP17H01265.
Funding Information:
This work was financially supported by JSPS KAKENHI, grant nos. JP18H03902, JP17K18993, and JP17H01265.
Publisher Copyright:
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2020/2/1
Y1 - 2020/2/1
N2 - For a better understanding of the exciton decay process in thermally activated delayed fluorescence (TADF) emitters, the intersystem crossing rate, kISC, is one of the important physical constants that have to be determined. Herein, a method to calculate the kISC value from photoluminescence (PL) measurements is reconsidered. The kISC value can be determined at very low temperatures where delayed fluorescence (DF) is completely suppressed, as well as around room temperature where triplet excitons mainly decay into the ground state by emitting DF. However, there is a temperature range where the kISC value cannot be determined accurately because the influences of nonradiative decay paths can be neither ignored nor corrected. For such a temperature range, an alternative approach, which utilizes the temperature dependence of an observed PL decay rate, is presented. In this way, kISC values from 300 to 10 K are determined for thin films of two TADF emitters, i.e., 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene and 1,2-bis(carbazol-9-yl)-4,5-dicyanobenzene, which are known as 4CzIPN and 2CzPN, respectively.
AB - For a better understanding of the exciton decay process in thermally activated delayed fluorescence (TADF) emitters, the intersystem crossing rate, kISC, is one of the important physical constants that have to be determined. Herein, a method to calculate the kISC value from photoluminescence (PL) measurements is reconsidered. The kISC value can be determined at very low temperatures where delayed fluorescence (DF) is completely suppressed, as well as around room temperature where triplet excitons mainly decay into the ground state by emitting DF. However, there is a temperature range where the kISC value cannot be determined accurately because the influences of nonradiative decay paths can be neither ignored nor corrected. For such a temperature range, an alternative approach, which utilizes the temperature dependence of an observed PL decay rate, is presented. In this way, kISC values from 300 to 10 K are determined for thin films of two TADF emitters, i.e., 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene and 1,2-bis(carbazol-9-yl)-4,5-dicyanobenzene, which are known as 4CzIPN and 2CzPN, respectively.
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U2 - 10.1002/pssa.201900616
DO - 10.1002/pssa.201900616
M3 - Article
AN - SCOPUS:85074825245
VL - 217
JO - Physica Status Solidi (A) Applications and Materials Science
JF - Physica Status Solidi (A) Applications and Materials Science
SN - 1862-6300
IS - 3
M1 - 1900616
ER -