Harnessing Triplet Excited States by Fluorescent Dopant Utilizing Codoped Phosphorescent Dopant in Exciplex Host for Efficient Fluorescent Organic Light Emitting Diodes

2016 ◽  
Vol 5 (3) ◽  
pp. 1600749 ◽  
Author(s):  
Hyun-Gu Kim ◽  
Kwon-Hyeon Kim ◽  
Chang-Ki Moon ◽  
Jang-Joo Kim
Keyword(s):  
Excited States ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light ◽  
Triplet Excited States

Magnetic field effects on the quenching of triplet excitons in exciplex-based organic light emitting diodes

2018 ◽  
Vol 6 (21) ◽  
pp. 5721-5726 ◽  
Author(s):  
Peisen Yuan ◽  
Xianfeng Qiao ◽  
Donghang Yan ◽  
Dongge Ma
Keyword(s):  
Excited States ◽  
Light Emitting Diodes ◽  
Energy Levels ◽  
Organic Light Emitting Diodes ◽  
Magnetic Field Effects ◽  
Triplet Energy ◽  
Light Emitting ◽  
Organic Light ◽  
Triplet Excited States ◽  
Triplet Excitons

Triplet excited states in exciplex-based organic light emitting diodes (OLEDs) can be wasted by transferring their energy to the host material in a system with smaller triplet energy levels.

scholarly journals Delayed Fluorescence from Inverted Singlet and Triplet Excited States for Efficient Organic Light-Emitting Diodes

2021 ◽  
Author(s):  
Daigo Miyajima ◽  
Naoya Aizawa ◽  
Yong-Jin Pu ◽  
Atsuko Nihonyanagi ◽  
Ryotaro Ibuka ◽  
...  
Keyword(s):  
Excited States ◽  
Light Emitting Diodes ◽  
Energy Gap ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Positive Energy ◽  
Light Emitting ◽  
Organic Light ◽  
Spin Singlet ◽  
Triplet Excited States

Abstract Hund’s multiplicity rule states that for a given electronic configuration, a higher spin state has a lower energy. Rephrasing this rule for molecular excited states predicts a positive energy gap between spin-singlet and spin-triplet excited states, which has been consistent with numerous experimental observations over almost a century. Here, we report a fluorescent molecule that disobeys Hund’s rule, possessing a negative singlet–triplet energy gap of –11 meV. The energy inversion of the singlet and triplet excited states results in delayed fluorescence with short time constants of 0.2 μs, which anomalously decrease with decreasing temperature due to the emissive singlet character of the lowest-energy excited state. Organic light-emitting diodes using this molecule exhibited a fast transient electroluminescence decay with a peak external quantum efficiency of 17%, demonstrating potential implications for optoelectronic devices, including displays, lighting, and lasers.

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.

Towards boosting the exciton lifetime and efficiency of near-infrared aggregation induced emitters with hybridized local and charge transfer excited states: a multiscale study

2019 ◽  
Vol 7 (29) ◽  
pp. 8874-8887 ◽  
Author(s):  
Jianzhong Fan ◽  
Yuchen Zhang ◽  
Kai Zhang ◽  
Jie Liu ◽  
Guanyu Jiang ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Excited States ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Luminescence Efficiency ◽  
Exciton Lifetime ◽  
Organic Light ◽  
Promising Application

Fluorescent emitters with long exciton lifetime and high luminescence efficiency show promising application in organic light emitting diodes (OLEDs), especially those with an aggregation induced emission (AIE) feature.

scholarly journals Highly efficient sky blue electroluminescence from ligand-activated copper iodide clusters: Overcoming the limitations of cluster light-emitting diodes

2019 ◽  
Vol 5 (6) ◽  
pp. eaav9857 ◽  
Author(s):  
Mingchen Xie ◽  
Chunmiao Han ◽  
Qianqian Liang ◽  
Jing Zhang ◽  
Guohua Xie ◽  
...  
Keyword(s):  
Excited States ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light ◽  
Molecular Transition ◽  
Optical Applications ◽  
Further Development ◽  
Cluster Unit

Organic light-emitting diodes using cluster emitters have recently emerged as a flexible optoelectronic platform to extend their biological and optical applications. However, their inefficient cluster-centered excited states and deficient electrical properties limit device performance. Here, we introduce donor groups in organic ligands to form ligand-activated clusters, enabling the fabrication of the first cluster-based sky blue–emitting device with a record 30- and 8-fold increased luminance and external quantum efficiency up to ~7000 nits and ~8%, respectively. We show that the electron-donating effect of donor groups can enhance ligand-centered transitions and thoroughly eliminate cluster-centered excited states by delocalizing the molecular transition orbitals from the cluster unit to the ligand, leading to 13-fold increased photoluminescence quantum yield. In turn, the excellent rigidity and photostability of the cluster unit improve the color purity and efficiency stability of the devices. These results will motivate the further development of high-performance optoelectronic clusters by ligand engineering.

Planarized intramolecular charge transfer on triphenylamine-modified pyrazine and its application in organic light-emitting diodes

2020 ◽  
Vol 8 (14) ◽  
pp. 4754-4762 ◽  
Author(s):  
Bing Zhang ◽  
Haozhong Wu ◽  
Zhiming Wang ◽  
Anjun Qin ◽  
Ben Zhong Tang
Keyword(s):  
Charge Transfer ◽  
Excited States ◽  
Ground State ◽  
Light Emitting Diodes ◽  
Intramolecular Charge Transfer ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light

PLICT molecules have twisted structures in the ground state, which are conducive to transport, while the planar conformations of the excited states facilitate radiation. Based on these advantages, they can serve as excellent emitters and hosts in OLEDs.

scholarly journals Triphenylamine disubstituted naphthalene diimide: elucidation of excited states involved in TADF and application in near-infrared organic light emitting diodes

2018 ◽  
Vol 6 (30) ◽  
pp. 8219-8225 ◽  
Author(s):  
Heather F. Higginbotham ◽  
Piotr Pander ◽  
Renata Rybakiewicz ◽  
Marc K. Etherington ◽  
Subashani Maniam ◽  
...  
Keyword(s):  
Excited States ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Organic Light ◽  
Naphthalene Diimide

A new TADF emitter is presented showing near-infrared efficient emission.

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