Triplet annihilation exceeding spin statistical limit in highly efficient fluorescent organic light-emitting diodes

2009 ◽  
Vol 106 (12) ◽  
pp. 124510 ◽  
Author(s):  
D. Y. Kondakov ◽  
T. D. Pawlik ◽  
T. K. Hatwar ◽  
J. P. Spindler
Keyword(s):  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Highly Efficient ◽  
Organic Light ◽  
Statistical Limit

scholarly journals Triplet–triplet annihilation in highly efficient fluorescent organic light-emitting diodes: current state and future outlook

2015 ◽  
Vol 373 (2044) ◽  
pp. 20140321 ◽  
Author(s):  
Denis Y. Kondakov
Keyword(s):  
Light Emitting Diodes ◽  
Practical Importance ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Highly Efficient ◽  
Organic Light ◽  
Statistical Limit ◽  
Special Cases ◽  
Triplet Triplet Annihilation

Studies of delayed electroluminescence in highly efficient fluorescent organic light-emitting diodes (OLEDs) of many dissimilar architectures indicate that the triplet–triplet annihilation (TTA) significantly increases yield of excited singlet states—emitting molecules in this type of device thereby contributes substantially to their efficiency. Towards the end of the 2000s, the essential role of TTA in realizing highly efficient fluorescent devices was widely recognized. Analysis of a diverse set of fluorescent OLEDs shows that high efficiencies are often cor-related to TTA extents. It is therefore likely that it is the long-term empirical optimization of OLED efficiencies that has resulted in fortuitous emergence of TTA as a large and ubiquitous contributor to efficiency. TTA contributions as high as 20–30% are common in the state-of-the-art OLEDs, and even become dominant in special cases, where TTA is shown to substantially exceed the spin-statistical limit. The fundamental features of OLED efficiency enhancement via TTA—molecular structure-dependent contributions, current density-dependent intensities in practical devices and frequently observed antagonistic relationships between TTA extent and OLED lifetime—came to be understood over the course of the next few years. More recently, however, there was much less reported progress with respect to all-important quantitative details of the TTA mechanism. It should be emphasized that, to this day and despite the decades of work on improving blue phosphorescent OLEDs as well as the recent advent of thermally activated delayed fluorescence OLEDs, the majority of practical blue OLEDs still rely on TTA. Considering such practical importance of fluorescent blue OLEDs, the design of blue OLED-compatible materials capable of substantially exceeding the spin-statistical limit in TTA, elimination of the antagonistic relationship between TTA-related efficiency gains and lifetime losses, and designing devices with an extended range of current densities producing near-maximum TTA electroluminescence are the areas where future improvements would be most beneficial.

Novel Carbazole-based Multifunctional Materials with Hybridized Local and Charge-Transfer Excited State Acting as Deep Blue Emitters and Phosphorescent Hosts for Highly Efficient Organic Light-Emitting Diodes

2021 ◽  
Author(s):  
Haitao Zhou ◽  
Mengna Yin ◽  
Zhenhong Zhao ◽  
Yanqin Miao ◽  
Xin Jin ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Multifunctional Materials ◽  
Light Emitting ◽  
Highly Efficient ◽  
Deep Blue ◽  
Organic Light ◽  
Blue Emitters

In this work, two carbazole- and benzo[d]oxazole-based novel multifunctional materials with hybridized local and charge-transfer (HLCT) characteristic, namely OCI and OCT, which could act as deep-blue fluorophors and phosphorescent hosts,...

Efficient organic light-emitting diodes based on iridium(III) complexes containing indolo[3,2,1-jk]carbazole derivatives with narrow emission bandwidths and low efficiency roll offs

2021 ◽  
Author(s):  
Xiang-Ji Liao ◽  
Jin-Jun Zhu ◽  
Li Yuan ◽  
Zhi-Ping Yan ◽  
Xu-Feng Luo ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Carbazole Derivatives ◽  
Highly Efficient ◽  
Organic Light ◽  
Low Efficiency ◽  
Narrow Emission

In this work, two cyclometalated ligands 2-(pyridin-2-yl)indolo[3,2,1-jk]carbazole (pyidcz) and 2-(4-(trifluoromethyl)pyridin-2-yl)indolo[3,2,1-jk]carbazole (tfpyidcz) using indolo[3,2,1-jk]carbazole unit were synthesized for highly efficient iridium(III) complexes (pyidcz)2Ir(tmd) and (tfpyidcz)2Ir(tmd) (tmd = 2,2,6,6-tetramethyl-3,5-heptanedione). The two Ir(III)...

Highly efficient blue phosphorescent organic light-emitting diodes with low operation voltage

2021 ◽  
Vol 142 ◽  
pp. 107229
Author(s):  
Qi Zhu ◽  
Liang Zhou ◽  
Weiqiang Liu ◽  
Yingjie Cui ◽  
Ruixia Wu ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Highly Efficient ◽  
Organic Light ◽  
Blue Phosphorescent

Highly efficient organic light-emitting diodes (OLEDs) based on an iridium complex with rigid cyclometalated ligand

2010 ◽  
Vol 11 (4) ◽  
pp. 632-640 ◽  
Author(s):  
Guanghui Zhang ◽  
Ho-Hsiu Chou ◽  
Xiaoqing Jiang ◽  
Peipei Sun ◽  
Chien-Hong Cheng ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Iridium Complex ◽  
Light Emitting ◽  
Highly Efficient ◽  
Organic Light ◽  
Cyclometalated Ligand

Ultrathin MoO3Layers in Composite Metal Electrodes: Improved Optics Allow Highly Efficient Organic Light‐Emitting Diodes

2018 ◽  
Vol 7 (3) ◽  
pp. 1801262 ◽  
Author(s):  
Yungui Li ◽  
Zheng Tang ◽  
Christian Hänisch ◽  
Paul‐Anton Will ◽  
Milan Kovačič ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Metal Electrodes ◽  
Light Emitting ◽  
Highly Efficient ◽  
Organic Light
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