Carbene metal amide photoemitters: tailoring conformationally flexible amides for full color range emissions including white-emitting OLED

Romanov, Alexander S.; Jones, Saul T. E.; Gu, Qinying; Conaghan, Patrick J.; Drummond, Bluebell H.; Feng, Jiale; Chotard, Florian; Buizza, Leonardo R. V.; Foley, Morgan; Linnolahti, Mikko; Credgington, Dan; Bochmann, Manfred

doi:10.1039/c9sc04589a

Cited by 103 publications

(162 citation statements)

References 43 publications

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“…More recently, impressive efforts on the structure modification on (carbene)M(I)(amide) complexes, for example (carbene)Au(I)(amide), have been described to achieve efficient emitters with excellent electroluminescent properties. [ 96 ]…”

Section: Emitters For Application In Oledsmentioning

confidence: 99%

A Brief History of OLEDs—Emitter Development and Industry Milestones

et al. 2021

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Organic light‐emitting diodes (OLEDs) have come a long way ever since their first introduction in 1987 at Eastman Kodak. Today, OLEDs are especially valued in the display and lighting industry for their promising features. As one of the research fields that equally inspires and drives development in academia and industry, OLED device technology has continuously evolved over more than 30 years. OLED devices have come forward based on three generations of emitter materials relying on fluorescence (first generation), phosphorescence (second generation), and thermally activated delayed fluorescence (third generation). Furthermore, research in academia and industry toward the fourth generation of OLEDs is in progress. Excerpts from the history of green, orange‐red, and blue OLED emitter development on the side of academia and milestones achieved by key players in the industry are included in this report.

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Section: Emitters For Application In Oledsmentioning

confidence: 99%

A Brief History of OLEDs—Emitter Development and Industry Milestones

et al. 2021

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“…Carbene-metal-amides (CMA) are a large family of organometallic donor-bridge-acceptor photoemitters that are promising candidates for thin-film light-emitting diodes. [1][2][3][4][5][6] CMA1, as the archetype of this group of molecules, employs cyclic (alkyl)(amino)carbene (CAAC) acceptor and carbazole (Cz) donor bridged by a gold (Au) atom, showing high photoluminescence quantum efficiency (80-90%) in solid films from states involving electron transfer from donor to acceptor, good chemical stability and fast intersystem crossing. [1][2][3][4][5][6] The σ-donating nature of the carbene ligand leads to a large permanent electrostatic dipole moment in the ground state.…”

Section: Introductionmentioning

confidence: 99%

Carbene–Metal–Amide Polycrystalline Materials Feature Blue Shifted Energy yet Unchanged Kinetics of Emission

et al. 2020

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The nature of carbene-metal-amide (CMA) photoluminescence in the solid state is explored through spectroscopic and quantum-chemical investigations on a representative Au-centred molecule. The crystalline phase offers well-defined coplanar geometries-enabling the link between molecular conformations and photophysical properties to be unravelled. We show that a combination of restricted torsional distortion and molecular electronic polarisation blueshift the charge-transfer emission by around 400 meV in the crystalline versus the amorphous phase, through energetically raising the less-dipolar S 1 state relative to S 0 . This blueshift brings the lowest charge-transfer states very close to the localised carbazole triplet state, whose structured emission is observable at low temperature in the polycrystalline phase. Moreover, we discover that the rate of intersystem crossing and emission kinetics are unaffected by the extent of torsional distortion. We conclude that more coplanar triplet equilibrium conformations control the photophysics of CMAs.

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“…At small HOMO-LUMO overlap, one obtains small exchange interaction and hence, a small ∆E(S1-T1) gap (as required for TADF materials), however, as well as a slow S1→S0 transition rate [37,48]. For completeness, it is remarked that design of materials with faster S1→S0 transition rates and small gaps ∆E(S1-T1) is highly attractive and indeed, became possible recently [40][41][42][43][44]52]. Interestingly, the emission intensity at ambient temperature represents a combined phosphorescence and TADF.…”

Section: Detailed Case Study Of Cu2i2(ph2ppy)3 1-i the Lowest Excited Triplet And Singlet Statesmentioning

confidence: 99%

P^N bridged Cu(I) Dimers Featuring both TADF and Phosphorescence. From Overview Towards Detailed Case Study of the Excited Singlet and Triplet States.

Hofbeck¹,

Niehaus²,

Fleck³

et al. 2021

Preprint

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We present an overview over eight brightly luminescent Cu(I) dimers of the type Cu2X2(PN)3 with X = Cl, Br, I and P^N = 2-diphenylphosphino-pyridine (Ph2Ppy), 2-diphenylphosphino-pyrimidine (Ph2Ppym), 1-diphenylphosphino-isoquinoline (Ph2Piqn) including three new crystal structures (Cu2Br2(Ph2Ppy)3, 1-Br, Cu2I2(Ph2Ppym)3, 2-I, and Cu2I2(Ph2Piqn)3, 3-I). However, we mainly focus on their photo-luminescence properties. All compounds exhibit combined thermally activated delayed fluorescence (TADF) and phosphorescence at ambient temperature. Emission color, decay time, and quantum yield varies over large ranges. For deeper characterization, we select Cu2I2(Ph2Ppy)3, 1-I, showing a quantum yield of 81 %. DFT and SOC-TDDFT calculations provide insight into the electronic structures of the singlet S1 and triplet T1 states. Both stem from metal+iodide-to-ligand charge transfer transitions. Evaluation of the emission decay dynamics, measured from 1.2 ≤ T ≤ 300 K, gives ∆E(S1-T1) = 380 cm-1 (47 meV), a transition rate of k(S1→S0) = 2.25×106 s-1 (445 ns), T1 zero-field splittings, transition rates from the triplet substates, and spin-lattice relaxation times. We also discuss the interplay of S1-TADF and T1-phosphorescence. The combined emission paths shorten the overall decay time. For OLED applications, utilization of both singlet and triplet harvesting can be highly favorable for improvement of the device performance.

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Carbene metal amide photoemitters: tailoring conformationally flexible amides for full color range emissions including white-emitting OLED

Abstract: Conformationally flexible “Carbene–Metal–Amide” (CMA) complexes of copper and gold show photoemissions across the visible spectrum, including mechanochromic behavior which led to the first CMA-based white light-emitting OLED.

Cited by 103 publications

References 43 publications

A Brief History of OLEDs—Emitter Development and Industry Milestones

A Brief History of OLEDs—Emitter Development and Industry Milestones

Carbene–Metal–Amide Polycrystalline Materials Feature Blue Shifted Energy yet Unchanged Kinetics of Emission

P^N bridged Cu(I) Dimers Featuring both TADF and Phosphorescence. From Overview Towards Detailed Case Study of the Excited Singlet and Triplet States.

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