Study of Methyl-Carbazole Derivatives for Thermally Activated Delayed Fluorescence Emitters

2017 ◽  
Vol 17 (10) ◽  
pp. 7319-7322
Author(s):  
Geon Hyeong Lee ◽  
Young Sik Kim
Keyword(s):  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Carbazole Derivatives ◽  
Thermally Activated

scholarly journals Impurity Conundrum of Organic Room Temperature Afterglow

2019 ◽  
Author(s):  
Chengjian Chen ◽  
Zhenguo Chi ◽  
Kok Chan Chong ◽  
Andrei S. Batsanov ◽  
Zhan Yang ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Room Temperature ◽  
Functional Materials ◽  
Delayed Fluorescence ◽  
Impurity Effect ◽  
Thermally Activated Delayed Fluorescence ◽  
Carbazole Derivatives ◽  
Thermally Activated ◽  
Commercial Sources ◽  
Triplet Excited States

<p>Commercial carbazole has been widely used to synthesize organic functional materials that entwine with the recent breakthroughs in thermally activated delayed fluorescence, organic luminescent radicals and organic laser diodes. Recently, the strategy of stabilizing triplet excited states in carbazole derivatives ignited the booming development of organic room temperature afterglow (RTA). The unusual RTA of carbazole and its derivatives was elaborated by crystal quality and packing. However, impurity hypotheses in organic RTA have been under debate for nearly a century. Here we show that an isomer of carbazole, accompanying the commercial sources with less than 0.5%, is the key to activating RTA for many carbazole derivatives. As compared to commercial carbazole, the fluorescence of lab-synthesized carbazole is blue-shifted by 54 nm and the well-known RTA disappears. The same phenomenon is also observed for a series of carbazole derivatives. Interestingly, even 0.01% isomer doping could yield the reported RTA. Our results demonstrate that the isomer doping in carbazole derivatives is responsible for their RTA. The impurity effect has also been confirmed for <a>dibenzothiophene</a> based RTA. We anticipate that isomer doping effect is applicable to many organic semiconductors derived from commercial carbazole, which will drive the review of organic functional materials in optoelectronics.</p>

Thermally Activated Delayed Fluorescence (Green) in Undoped Film and Exciplex Emission (Blue) in Acridone–Carbazole Derivatives for OLEDs

2018 ◽  
Vol 123 (2) ◽  
pp. 1003-1014 ◽  
Author(s):  
Qamar T. Siddiqui ◽  
Ankur A. Awasthi ◽  
Prabhjyot Bhui ◽  
Mohammad Muneer ◽  
Kuttay R. S. Chandrakumar ◽  
...  
Keyword(s):  
Delayed Fluorescence ◽  
Undoped Film ◽  
Thermally Activated Delayed Fluorescence ◽  
Carbazole Derivatives ◽  
Thermally Activated ◽  
Exciplex Emission

Blue thermally activated delayed fluorescence materials based on bi/tri-carbazole derivatives

2018 ◽  
Vol 58 ◽  
pp. 238-244 ◽  
Author(s):  
Wenjuan Zhang ◽  
Ye-Xin Zhang ◽  
Xiao-Qing Zhang ◽  
Xiang-Yang Liu ◽  
Jian Fan ◽  
...  
Keyword(s):  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Carbazole Derivatives ◽  
Thermally Activated

scholarly journals Impurity Conundrum of Organic Room Temperature Afterglow

2019 ◽  
Author(s):  
Chengjian Chen ◽  
Zhenguo Chi ◽  
Kok Chan Chong ◽  
Andrei S. Batsanov ◽  
Zhan Yang ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Room Temperature ◽  
Functional Materials ◽  
Delayed Fluorescence ◽  
Impurity Effect ◽  
Thermally Activated Delayed Fluorescence ◽  
Carbazole Derivatives ◽  
Thermally Activated ◽  
Commercial Sources ◽  
Triplet Excited States

<p>Commercial carbazole has been widely used to synthesize organic functional materials that entwine with the recent breakthroughs in thermally activated delayed fluorescence, organic luminescent radicals and organic laser diodes. Recently, the strategy of stabilizing triplet excited states in carbazole derivatives ignited the booming development of organic room temperature afterglow (RTA). The unusual RTA of carbazole and its derivatives was elaborated by crystal quality and packing. However, impurity hypotheses in organic RTA have been under debate for nearly a century. Here we show that an isomer of carbazole, accompanying the commercial sources with less than 0.5%, is the key to activating RTA for many carbazole derivatives. As compared to commercial carbazole, the fluorescence of lab-synthesized carbazole is blue-shifted by 54 nm and the well-known RTA disappears. The same phenomenon is also observed for a series of carbazole derivatives. Interestingly, even 0.01% isomer doping could yield the reported RTA. Our results demonstrate that the isomer doping in carbazole derivatives is responsible for their RTA. The impurity effect has also been confirmed for <a>dibenzothiophene</a> based RTA. We anticipate that isomer doping effect is applicable to many organic semiconductors derived from commercial carbazole, which will drive the review of organic functional materials in optoelectronics.</p>

Solvent Dependence of Structural Dynamics and Spin-flip Processes in 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (ortho-3CzBN)

2020 ◽  
Author(s):  
Masaki Saigo ◽  
Kiyoshi Miyata ◽  
Hajime Nakanotani ◽  
Chihaya Adachi ◽  
Ken Onda
Keyword(s):  
Dft Calculations ◽  
Excited States ◽  
Structural Changes ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Solvent Dependence ◽  
Acetonitrile Solutions

We have investigated the solvent-dependence of structural changes along with intersystem crossing of a thermally activated delayed fluorescence (TADF) molecule, 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (o-3CzBN), in toluene, tetrahydrofuran, and acetonitrile solutions using time-resolved infrared (TR-IR) spectroscopy and DFT calculations. We found that the geometries of the S1 and T1 states are very similar in all solvents though the photophysical properties mostly depend on the solvent. In addition, the time-dependent DFT calculations based on these geometries suggested that the thermally activated delayed fluorescence process of o-3CzBN is governed more by the higher-lying excited states than by the structural changes in the excited states.<br>

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