Evolution of emission manners of organic light-emitting diodes: From emission of singlet exciton to emission of doublet exciton

2016 ◽  
Vol 27 (8) ◽  
pp. 1345-1349 ◽  
Author(s):  
Ablikim Obolda ◽  
Ming Zhang ◽  
Feng Li
Keyword(s):  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Singlet Exciton ◽  
Organic Light

A high fluorescence rate is key for stable blue organic light-emitting diodes

2018 ◽  
Vol 6 (29) ◽  
pp. 7728-7733 ◽  
Author(s):  
Zhusen Liu ◽  
Fangyi Cao ◽  
Taiju Tsuboi ◽  
Yan Yue ◽  
Chao Deng ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Critical Factor ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Singlet Exciton ◽  
Thermally Activated ◽  
Organic Light ◽  
Exciton Annihilation ◽  
High Fluorescence

Singlet–singlet exciton annihilation (SSA) is found to be a critical factor for the decomposition of blue thermally activated delayed fluorescence (TADF) emitters in organic light-emitting diodes (OLEDs).

Degradation of fluorescent organic light emitting diodes caused by quenching of singlet and triplet excitons

2020 ◽  
Vol 8 (42) ◽  
pp. 14873-14879
Author(s):  
Duy Cong Le ◽  
Duong Dai Nguyen ◽  
Savanna Lloyd ◽  
Toshi-kazu Suzuki ◽  
Hideyuki Murata
Keyword(s):  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Singlet Exciton ◽  
Organic Light ◽  
Positively Charged ◽  
Triplet Excitons ◽  
Triplet Triplet Annihilation

The initial luminescence loss of fluorescent OLEDs utilizing triplet–triplet annihilation is not only caused by quenching of singlet exciton with neutral quenchers but also by that of triplet excitons with positively charged quenchers.

Singlet exciton diffusion length in organic light-emitting diodes

2012 ◽  
Vol 85 (24) ◽  
Author(s):  
Simone Hofmann ◽  
Thomas C. Rosenow ◽  
Malte C. Gather ◽  
Björn Lüssem ◽  
Karl Leo
Keyword(s):  
Light Emitting Diodes ◽  
Diffusion Length ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Singlet Exciton ◽  
Exciton Diffusion ◽  
Exciton Diffusion Length ◽  
Organic Light

scholarly journals Triplet–triplet upconversion enhanced by spin–orbit coupling in organic light-emitting diodes

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Ryota Ieuji ◽  
Kenichi Goushi ◽  
Chihaya Adachi
Keyword(s):  
Excited States ◽  
Light Emitting Diodes ◽  
Energy Levels ◽  
Molecular Structures ◽  
Organic Light Emitting Diodes ◽  
Triplet Energy ◽  
Light Emitting ◽  
Singlet Exciton ◽  
Organic Light ◽  
Triplet Excited States

AbstractTriplet–triplet upconversion, in which two triplet excitons are converted to one singlet exciton, is a well-known approach to exceed the limit of electroluminescence quantum efficiency in conventional fluorescence-based organic light-emitting diodes. Considering the spin multiplicity of triplet pairs, upconversion efficiency is usually limited to 20%. Although this limit can be exceeded when the energy of a triplet pair is lower than that of a second triplet excited state, such as for rubrene, it is generally difficult to engineer the energy levels of higher triplet excited states. Here, we investigate the upconversion efficiency of a series of new anthracene derivatives with different substituents. Some of these derivatives show upconversion efficiencies close to 50% even though the calculated energy levels of the second triplet excited states are lower than twice the lowest triplet energy. A possible upconversion mechanism is proposed based on the molecular structures and quantum chemical calculations.

scholarly journals Organic light-emitting diodes: theoretical understanding of highly efficient materials and development of computational methodology

2016 ◽  
Vol 4 (2) ◽  
pp. 224-239 ◽  
Author(s):  
Zhigang Shuai ◽  
Qian Peng
Keyword(s):  
Bound States ◽  
Light Emitting Diodes ◽  
Resonance Raman Spectroscopy ◽  
Polymeric Materials ◽  
Decay Rates ◽  
Organic Light Emitting Diodes ◽  
Theoretical Understanding ◽  
Light Emitting ◽  
Singlet Exciton ◽  
Organic Light

Abstract Theoretical understanding of organic light-emitting diodes started from the quest to the nature of the primary excitation in organic molecular and polymeric materials. We found the electron correlation strength, bond-length alternation as well as the conjugation extent have strong influences on the orderings of the lowest lying excited states through the first application of density matrix renormalization group theory to quantum chemistry. The electro-injected free carriers (with spin 1/2) can form both singlet and triplet bound states. We found that the singlet exciton formation ratio can exceed the conventional 25% spin statistics limit. We proposed a vibration correlation function formalism to evaluate the excited-state decay rates, which is shown to not only give reasonable estimations for the quantum efficiency but also a quantitative account for the aggregation-induced emission (AIE). It is suggested to unravel the AIE mechanism through resonance Raman spectroscopy.

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