Temperature effects on the intramolecular decay of the lowest triplet state of benzophenone

Jones, Peter; Calloway, A. R.

doi:10.1016/0009-2614(71)80329-9

Cited by 37 publications

(17 citation statements)

References 12 publications

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“…This was the beginning of experimental study on TADF. Since the 1960s, TADF has been observed from various compounds such as eosin [2], benzophenone [3], aromatic thiones [4], and fullerenes [5,6], suggesting that TADF emitters have diverse chemical structures.…”

Section: Thermally Activated Delayed Fluorescence and Its Applicationmentioning

confidence: 99%

Highly efficient electroluminescence from purely organic donor–acceptor systems

Shizu

Lee

Tanaka

et al. 2015

Pure and Applied Chemistry

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Thermally activated delayed fluorescence (TADF) emitters are third-generation electroluminescent materials that realize highly efficient organic light-emitting diodes (OLEDs) without using rare metals. Here, after briefly reviewing the principles of TADF and its use in OLEDs, we report a sky-blue TADF emitter, 9-(4-(benzo[d]thiazol-2-yl)phenyl)-N 3 ,N 3 ,N 6 ,N 6 -tetraphenyl-9H-carbazole-3,6-diamine (DAC-BTZ). DAC-BTZ is a purely organic donor-acceptor-type molecule with a small energy difference between its lowest excited singlet state and lowest triplet state of 0.18-0.22 eV according to fluorescence and phosphorescence spectra of a DAC-BTZ-doped film. In addition, the doped film exhibits a high photoluminescence quantum yield of 0.82. Time-resolved photoluminescence measurements of the doped film confirm that DAC-BTZ emits TADF. An OLED containing DAC-BTZ as an emitter exhibits a maximum external quantum efficiency (EQE) of 10.3 %, which exceeds those obtained with conventional fluorescent emitters (5-7.5 %). TADF from DAC-BTZ makes a large contribution to the high EQE of its OLED.

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Section: Thermally Activated Delayed Fluorescence and Its Applicationmentioning

confidence: 99%

Highly efficient electroluminescence from purely organic donor–acceptor systems

Shizu

Lee

Tanaka

et al. 2015

Pure and Applied Chemistry

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“…The factor of 1/3 in this equation accounts for the three-fold degeneracy of the triplet state. 40 Fig. 3 shows the luminescence decay traces for two TADF emitters, one with a silver ion and the other a copper ion.…”

Section: ''Simple'' Kinetic Picture Of Tadfmentioning

confidence: 99%

Thermally assisted delayed fluorescence (TADF): fluorescence delayed is fluorescence denied

2020

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“…Indeed, TADF, also known as E‐type delayed fluorescence in the early literature, is a photophysical mechanism that was first reported in 1961, when eosin was observed to emit delayed fluorescence in ethanol at 70 °C (Figure ). Other examples of organic molecules that have been shown to emit via TADF include benzophenone, aromatic thiones, thioketones and 9,10‐anthraquinone . Although the vast majority of effort and attention is devoted to purely organic TADF emitters, the very first TADF emitters applied in OLED devices stemmed from more traditional organometallic complexes and, interestingly, the TADF‐emitter development history showed a gradual transition from heavy metals (e.g., Ir and Pt) to lighter elements (e.g., C and N) .…”

Section: Introductionmentioning

confidence: 99%

Purely Organic Thermally Activated Delayed Fluorescence Materials for Organic Light‐Emitting Diodes

2017

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The earliest account of electroluminescence, the process of converting electrical energy into light, using organic materials can be traced back to 1963 when Pope et al. applied a direct current to an anthracene single crystal under a bias of 400 V using silver-paste electrodes. [3] Although anthracene fluorescence was observed, a driving voltage of 400 V is evidently not viable in practical applications. The seminal breakthrough in the development of OLEDs appeared in 1987 when Tang and Van Slyke reported a double-layered device using tris(8-hydroxyquinoline)aluminum (Alq 3 ) as the emitting and electron-transporting layer. [1] The green-emitting device showed an external quantum efficiency (EQE) of about 1% when driven at less than 10 V. This marked the dawn of OLED development and tremendous interest and effort from both academia and industry have followed subsequent to this pioneering work, resulting in the ultimate wide-scale commercialization of OLEDs, particularly for display applications.In order to make OLEDs commercially viable for lighting applications, where the cost per unit must be competitive with presently used technology, there are a number of challenges that must be overcome aside from reducing the production cost. The organic emitters should have high photoluminescence quantum yields (PLQYs), which directly impact the device efficiency. The energy levels of the frontier molecular orbitals (i.e., highest occupied and lowest unoccupied molecular oribitals (HOMOs and LUMOs)) of each of the layers in the device should be optimally relatively aligned in order to: i) minimize the barrier to charge injection, and ii) control the recombination region within the device, which greatly affects both the device efficiency and lifetime. [4] The organic materials must demonstrate sufficient thermal stability to be compatible with their vacuum deposition during device fabrication or produce thin films of suitable morphology when spin-coated during solution processing. Regardless of the fabrication method, the organic material must be morphologically stable during device operation when Joule heat is produced in the device. [5] Aside from the aforementioned challenges, another key issue to address is the management of hole and electron recombination within the device, each possessing their own spin. Unlike photoexcitation, in which mainly singlet excited states are produced in the organic emitters, exciton formation through charge (hole and electron) recombination in OLED devices results in 25% singlets and 75% triplets, according to The design of thermally activated delayed fluorescence (TADF) materials both as emitters and as hosts is an exploding area of research. The replacement of phosphorescent metal complexes with inexpensive organic compounds in electroluminescent (EL) devices that demonstrate comparable performance metrics is paradigm shifting, as these new materials offer the possibility of developing low-cost lighting and displays. Here, a comprehensive review of TADF materials is presented, with a...

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Temperature effects on the intramolecular decay of the lowest triplet state of benzophenone

Cited by 37 publications

References 12 publications

Highly efficient electroluminescence from purely organic donor–acceptor systems

Highly efficient electroluminescence from purely organic donor–acceptor systems

Thermally assisted delayed fluorescence (TADF): fluorescence delayed is fluorescence denied

Purely Organic Thermally Activated Delayed Fluorescence Materials for Organic Light‐Emitting Diodes

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