E-Type Delayed Fluorescence of a Phosphine-Supported Cu2(μ-NAr2)2 Diamond Core: Harvesting Singlet and Triplet Excitons in OLEDs

Deaton, Joseph C.; Switalski, Steven C.; Kondakov, Denis Y.; Young, Ralph H.; Pawlik, Thomas D.; Giesen, David J.; Harkins, Seth B.; Miller, Alex J.; Mickenberg, Seth F.; Peters, Jonas C.

doi:10.1021/ja1004575

Cited by 463 publications

(356 citation statements)

References 69 publications

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“…In terms of devices made form E-type emitters, one needs to have a high total luminescence quantum yield and a small Δ ST . The diamond core complex reported by Deaton yields green devices with external quantum efficiency of 16.1%, close to that obtainable with Ir-based phosphors [128]. Further, there are also reports of all organic emitters which have low Δ ST and appreciable E-type contribution [132].…”

Section: Alternative Ways To Produce Singlet Excitons From Triplet Stsupporting

confidence: 60%

“…Hence at low temperature, phosphorescence dominates (radiative) triplet decay but at high temperature delayed singlet emission dominates. Theoretical modelling of the phosphine-supported Cu 2 ( -NAr 2 ) 2 diamond core complex of Deaton et al [128,129] shows a very small exchange splitting of 750 cm −1 and clearly identifies the HOMO on the Cu 2 -N 2 core with the LUMO on the peripheral aryl bringing units. The lowest excited state is found to comprise >90% of this HOMO-LUMO transition and hence nearly pure CT.…”

Section: Alternative Ways To Produce Singlet Excitons From Triplet Stmentioning

confidence: 95%

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Singlet Generation from Triplet Excitons in Fluorescent Organic Light-Emitting Diodes

Monkman

2013

ISRN Materials Science

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A potential major drawback with organic light-emitting devices, (OLEDs) is the limit of 25% singlet exciton production through spin-dependent charge recombination. Recent device results, however, show that this limit does not hold and far higher efficiencies can be achieved in purely fluorescent-based systems (Wohlgenannt et al. (2012)). Here, the various routes by which triplet excitons can generate singlet states are discussed and their relative contributions to the overall electroluminescence yield are given. The materials requirements to obtain maximum singlet production from triplet states are discussed. These triplet contributions can give very high device yields for fluorescent emitters, which in the case of blue devices can be highly advantageous. Further, new devices architectures open up which are simple and have intrinsically low turn on voltages, ideal for large-area OLED lighting applications.

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Section: Alternative Ways To Produce Singlet Excitons From Triplet Stsupporting

confidence: 60%

Section: Alternative Ways To Produce Singlet Excitons From Triplet Stmentioning

confidence: 95%

Singlet Generation from Triplet Excitons in Fluorescent Organic Light-Emitting Diodes

Monkman

2013

ISRN Materials Science

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“…singlets only) EQE (%) Figure 1. Evolution of the efficiencies of the fluorescent OLEDs [1,[7][8][9][10][11][12]. (Online version in colour.…”

Section: Evolution Of Efficiencies Of Fluorescent Organic Light-emittmentioning

confidence: 99%

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

Kondakov

2015

Phil. Trans. R. Soc. A.

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137

119

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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.

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“…More recently, research focus has largely shifted to the mixed phosphine-diimine complexes [Cu(NN)(PP)] n+ (n = 0, 1) of neutral and cationic nature, for which an impressive enhancement of quantum yield was demonstrated reaching as high as 90%. 5,12,16,18,23,25,28 The emission observed originates mainly from MLCT excited states that makes possible tuning luminescence parameters through electronic and stereochemical properties of the ligands that stimulated further A general common feature of the Cu(I) complexes mentioned above is a conformationally rigid chelating bidentate phosphine that brings steric bulkiness and minimizes the undesired excited state distortions. It has to be noted that triphosphine ligands have been rarely used in the synthesis of Cu(I) species with only a few reports on luminescent compounds.…”

Section: Introductionmentioning

confidence: 99%

Alkynyl triphosphine copper complexes: synthesis and photophysical studies

et al. 2015

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E-Type Delayed Fluorescence of a Phosphine-Supported Cu₂(μ-NAr₂)₂ Diamond Core: Harvesting Singlet and Triplet Excitons in OLEDs

Cited by 463 publications

References 69 publications

Singlet Generation from Triplet Excitons in Fluorescent Organic Light-Emitting Diodes

Singlet Generation from Triplet Excitons in Fluorescent Organic Light-Emitting Diodes

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

Alkynyl triphosphine copper complexes: synthesis and photophysical studies

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