Simple, Fast, Bright, and Stable Light Sources

Tordera, Daniel; Meier, Sebastian; Lenes, Martijn; Costa, Rubén D.; Ortı́, Enrique; Sarfert, Wiebke; Bolink, Henk J.

doi:10.1002/adma.201104047

Cited by 153 publications

(167 citation statements)

References 28 publications

(4 reference statements)

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“…Pulsed-current driving has been demonstrated to lead to devices with longer lifetimes and faster response compared to fixed-current/voltage driving. 23 The dependence of the luminance and average voltage with time is depicted in Figure 9 and key parameters derived from the graphs are collected in Table 3. All the devices present a fast initial decrease of the voltage until a minimum stable value (2.3−2.7 V) is reached.…”

Section: Theoretical Calculationsmentioning

confidence: 99%

“…Nowadays, a wide variety of complexes has been designed and used to manufacture LEC devices covering the whole visible spectrum, 16,17,18,19 with high efficiencies, 20,21,22 top lifetimes, 23,24,25 and short turnon times. 26,27,28 However, it is still to be found a complex that allows the fabrication of a device that reunites all those characteristics and becomes suitable for real-life lighting applications.…”

Section: Introductionmentioning

confidence: 99%

“…The most common strategy to achieve such high stability has been the inclusion of bulky hydrophobic ligands to protect the coordination center. 23,29 However, bulky groups are known to slow down the migration of the ions in the device inducing long turn-on times. 30,31 Hence, there is still room to explore new strategies and ligands in search for higher performances and stabilities.…”

Section: Introductionmentioning

confidence: 99%

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Highly Stable and Efficient Light-Emitting Electrochemical Cells Based on Cationic Iridium Complexes Bearing Arylazole Ancillary Ligands

et al. 2017

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A series of bis-cyclometalated iridium(III) complexes of general formula [Ir(ppy)2(N∧N)][PF6] (ppy– = 2-phenylpyridinate; N∧N = 2-(1H-imidazol-2-yl)pyridine (1), 2-(2-pyridyl)benzimidazole (2), 1-methyl-2-pyridin-2-yl-1H-benzimidazole (3), 2-(4′-thiazolyl)benzimidazole (4), 1-methyl-2-(4′-thiazolyl)benzimidazole (5)) is reported, and their use as electroluminescent materials in light-emitting electrochemical cell (LEC) devices is investigated. [2][PF6] and [3][PF6] are orange emitters with intense unstructured emission around 590 nm in acetonitrile solution. [1][PF6], [4][PF6], and [5][PF6] are green weak emitters with structured emission bands peaking around 500 nm. The different photophysical properties are due to the effect that the chemical structure of the ancillary ligand has on the nature of the emitting triplet state. Whereas the benzimidazole unit stabilizes the LUMO and gives rise to a 3MLCT/3LLCT emitting triplet in [2][PF6] and [3][PF6], the presence of the thiazolyl ring produces the opposite effect in [4][PF6] and [5][PF6] and the emitting state has a predominant 3LC character. Complexes with 3MLCT/3LLCT emitting triplets give rise to LEC devices with luminance values 1 order higher than those of complexes with 3LC emitting states. Protecting the imidazole N–H bond with a methyl group, as in complexes [3][PF6] and [5][PF6], shows that the emissive properties become more stable. [3][PF6] leads to outstanding LECs with simultaneously high luminance (904 cd m–2), efficiency (9.15 cd A–1), and stability (lifetime over 2500 h).

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Section: Theoretical Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Highly Stable and Efficient Light-Emitting Electrochemical Cells Based on Cationic Iridium Complexes Bearing Arylazole Ancillary Ligands

et al. 2017

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“…The LEC device was driven using pulsed current methods with an average current density of 100 Am -2 using a duty cycle of 50%. 34 Details of the device preparation are explained in the Experimental section. Figure 3 shows the electroluminescent spectrum from ITO/PEDOT:PSS/ complex 1/Al device.…”

Section: Electroluminescent Propertiesmentioning

confidence: 99%

ANOMALOUS BEHAVIOR OF Ir(III) CYCLOMETALATED COMPLEXES: APPLICATION IN LIGHT-EMITTING ELECTROCHEMICAL CELLS

Dreyse

Loeb

Barrera

et al. 2014

J. Chil. Chem. Soc.

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The cationic Ir(III) complex with 7,8-benzoquinoline (bzq) as cyclometalating ligand and 4,4´-diterbutyl-2,2´-bipyridine (tBuB) as ancillary ligand, [Ir(bzq) 2 (tBuB)](PF 6 ) (1), was utilized in the fabrication of a light-emitting electrochemical cell (LEC). The photophysical properties and the characterization of the LEC device with this complex was compared with literature data for the analogous complex with 2-phenylpyridine (ppy), [Ir(ppy) 2 (tBuB)](PF 6 ) (2). Complex 1 showed blue shifted emission compared to complex 2. Surprisingly, complex 1 shows lower luminance, efficiency and stability in regard to 2. This behavior correlated well with the low values of quantum yield and lifetime, registered for complex 1 in solution. The performance observed is unexpected, taking into account the emission wavelengths recorded for each complex, and the lesser non radiative deactivation processes expected for a complex with a more rigid ligand as bzq. A possible explanation of this behavior is given in terms of the predominance of a fluorescent emission in the case of the complex 1 instead of a phosphorescent emission, as observed for complex 2.

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“…16,27,29 On the other hand, the discovery of stable, yellow iTMC-complex due to intramolecular π−π stacking interactions 33 and pulsed operation mode yielded devices with lifetimes exceeding 4000 h at maximum luminance over 650 cd/m 2 and subsecond turn-on times. 17 Recently, the approach of multiple π-stacking interactions yielded promising results also for red-emitting complexes, 18 making the iTMC-LECs together with their simple architecture very attractive for industrial roll-to-roll fabrication. 1,34 Combining the stability of semiconducting materials with their solution-based properties, colloidal QDs offer an alternative approach for large area lighting concepts thanks to their high color purity which is tunable over a broad spectral range by tailoring their size, shape, and composition.…”

Section: ■ Introductionmentioning

confidence: 99%

Quantum Dot/Light-Emitting Electrochemical Cell Hybrid Device and Mechanism of Its Operation

Frohleiks

Wepfer

Keleştemur

et al. 2016

ACS Appl. Mater. Interfaces

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A new type of light-emitting hybrid device based on colloidal quantum dots (QDs) and an ionic transition metal complex (iTMC) light-emitting electrochemical cell (LEC) is introduced. The developed hybrid devices show light emission from both active layers, which are combined in a stacked geometry. Time-resolved photoluminescence experiments indicate that the emission is controlled by direct charge injection into both the iTMC and the QD layer. The turn-on time (time to reach 1 cd/m 2 ) at constant voltage operation is significantly reduced from 8 min in the case of the reference LEC down to subsecond in the case of the hybrid device. Furthermore, luminance and efficiency of the hybrid device are enhanced compared to reference LEC directly after device turn-on by a factor of 400 and 650, respectively. We attribute these improvements to an increased electron injection efficiency into the iTMC directly after device turn-on.

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Simple, Fast, Bright, and Stable Light Sources

Cited by 153 publications

References 28 publications

Highly Stable and Efficient Light-Emitting Electrochemical Cells Based on Cationic Iridium Complexes Bearing Arylazole Ancillary Ligands

Highly Stable and Efficient Light-Emitting Electrochemical Cells Based on Cationic Iridium Complexes Bearing Arylazole Ancillary Ligands

ANOMALOUS BEHAVIOR OF Ir(III) CYCLOMETALATED COMPLEXES: APPLICATION IN LIGHT-EMITTING ELECTROCHEMICAL CELLS

Quantum Dot/Light-Emitting Electrochemical Cell Hybrid Device and Mechanism of Its Operation

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