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

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>

scholarly journals Lock-and-Key Exciplexes for Thermally Activated Delayed Fluorescence

2020 ◽  
Vol 02 (01) ◽  
pp. 001-010
Author(s):  
Constantin-Christian A. Voll ◽  
Georgios Markopoulos ◽  
Tony C. Wu ◽  
Matthew Welborn ◽  
Jens U. Engelhart ◽  
...  
Keyword(s):  
Density Functional ◽  
Materials Science ◽  
Visible Spectrum ◽  
Density Functional Theory Calculations ◽  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting Devices ◽  
Thermally Activated ◽  
Emission Color ◽  
Exciplex Emission

We combine synthetic supramolecular chemistry and materials science to develop novel exciplexes for thermally activated delayed fluorescence. Our approach starts from a bowl-shaped acceptor molecule for which we synthesize tailor-made donors that bind in a lock-and-key fashion. The donor design is guided by extensive density functional theory calculations of three independent donor families. The investigation of a large number of custom-synthesized donors allows us to derive empirical relationships for the prediction of the exciplex emission color. Incorporated within organic light-emitting devices, the lock-and-key exciplexes yield external quantum efficiencies of up to 5.4%, with potentially tunable emission color across the blue and green visible spectrum.

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>

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