Highly efficient platinum-based emitters for warm white light emitting diodes

Sicilia, Violeta; Fuertes, Sara; Chueca, Andrés J.; Arnal, Lorenzo; Martín, António; Perálvarez, M.; Botta, Chiara; Giovanella, Umberto

doi:10.1039/c9tc00747d

Cited by 14 publications

(34 citation statements)

References 46 publications

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“…The X-ray study of 6A , 6B , and 7A (Figures , S56, and S57 and Table ) confirmed their molecular structures showing a really distorted square-planar coordination environment for the metal with C(1)–Pt–C(10) and X(1)–Pt–X(2) (X = P for 6A and 6B , S for 7A ) bite angles of 79°–73°. Regarding the “Pt(C^C* A/B )” moiety, the Pt–C bond parameters are similar to those of reported platinacycles with N-heterocyclic carbenes, ,,,,− and the five-membered platinacycle and the Pt coordination plane result almost coplanar (Table ).…”

Section: Resultssupporting

confidence: 81%

“…5 and 1 μs, respectively. Thus, keeping all this in mind and the π-stacked packings reported in the X-ray structure of 7A (Figure S57), the LE band can be attributed to 3 ππ* transitions due to the formation of aggregates as a result of π–π interactions among C^C* groups from adjacent molecules. ,, Considering the analogous emission features (vibronic structure, energy and lifetime) of the HE band with those obtained in 2-MeTHF (10 –5 M, 77 K), it seems reasonable to assume the same emissive origin, 3 ILCT/ 3 MLCT for them.…”

Section: Resultsmentioning

confidence: 63%

“…If we compare the powder QY of 5B (7%) and 6B (57%), with [Pt(C^C* B )(P^P)]PF 6 (P^P = dppm, dppe, dppbz) [QY = 10–40%], having the same cyclometalated carbene (C^C* B ) but different P^P ligand, it can be observed the great influence of the chelating diphosphine. Also, compound 6B proved to be among or even better than the best blue Pt(II) emitters whether in solid state or doped film. ,,− ,− Nonetheless, the CIE coordinates (0.17, 0.30) slightly deviate from the desired ones for deep blue emitters (0.15, 0.22), see Figure .…”

Section: Resultsmentioning

confidence: 99%

“…Given the great interest in stable and efficient luminescent compounds and our previous results of bright-blue emitters using cyclometalated NHC complexes of Pt(II), − we decided to investigate new Pt(C^C*) systems with different chelating ancillary ligands that present varied steric and electronic properties. Thus, we prepared a new NHC cycloplatinated compound [Pt(C^C* A )ClMeCN] (HC^C* A -κC* A = 1-(4-(ethoxycarbonyl)phenyl)-3-methyl-1 H -benzimidazol-2-ylidene, 4A ) following our stepwise procedure.…”

Section: Introductionmentioning

confidence: 99%

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Cyclometalated NHCs Pt(II) Compounds with Chelating P^P and S^S Ligands: From Blue to White Luminescence

et al. 2020

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Ionic [Pt(C^C* A/B )(P^P)]PF 6 and neutral [Pt(C^C* A/B )(S^S)] complexes were designed and synthesized containing cyclometalated N-heterocyclic carbenes (C^C* A/B ) and diphosphines (P^P: dpfppe, dcypm) or dithiocarbamates (S^S: dmdtc, pdtc) as chelating ligands. Their structural and spectroscopic properties were investigated and found to be dependent on both cyclometalated (C^C* A/B ) and ancillary (P^P, S^S) ligands. The photophysical and computational studies for the [Pt(C^C* A/B )(P^P)] + complexes disclose the nature of the low-lying electronic transitions to be mainly intraligand charge transfer [ILCT (C^C* A/B )] with some contribution of ligand-to-ligand charge transfer (LL'CT) or ligand-to metal charge transfer (LMCT) for the dpfppe or dcypm derivatives, respectively. The blue and cyan emissions of PMMA films doped with the [Pt(C^C* A/B )(P^P)] + complexes exhibited very high quantum yields (QYs) reaching up to ∼90%. However, the low-energy absorptions and emissions of the [Pt(C^C* A/B )(S^S)] complexes in solution (rt or 77 K) arise from mixed ILCT [C^C* A/B ]/MLCT [dπ(Pt) → π*(C^C* A/B )] excited states, showing no change with the different S^S ligands. In solid-state and in doped films, these dithiocarbamate complexes, excluding 8B, display dual emissions with the high-energy vibronic band ( 3 ILCT / 3 MLCT) appearing together with an additional low-energy structureless band. The latter is attributed to 3 ππ* transitions originated from π-stacked aggregates, as reported in the X-ray structure of 7A. Thus, white light emissions can be obtained with photo-and colorimetric values lying inside the stipulated limits for general lighting applications; yet, they display low QY.

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cyclometalated NHCs Pt(II) Compounds with Chelating P^P and S^S Ligands: From Blue to White Luminescence

et al. 2020

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“…Having in mind that C,N-cyclometalated compounds with a poor π-acceptor neutral fragment like pyrazole instead of a pyridine would enlarge the energy gap and alter the emissive properties and that the aryl-pyrazole platinum compounds have been barely explored, − we decided to expand the investigation to a new synthon N n Bu 4 [Pt(C^N)(CN) 2 ] (HC^N = 1-(naphthalen-2-yl)-1 H -pyrazole, 4A ) whose cyclometalated skeleton (Pt(Naph^N)) also presents structural similarities with the N-heterocyclic carbene species (Pt(Naph^C*)) we have recently been investigating on. − Thus, compound N n Bu 4 [Pt(Naph^N)(CN) 2 ] ( 4A ) and the counterpart, N n Bu 4 [Pt(Naph^C*)(CN) 2 ] (HC^C*-κC* = 3-methyl-1-(naphthalen-2-yl)-1 H- imidazol-2-ylidene, 4B ), recently published by Kato and co-workers, have been reacted with TlPF 6 to afford neutral extended structures containing Pt–Tl dative bonds, [PtTl(Naph^E)(CN) 2 ] (E = pyrazole 5A , carbene 5B ). Structural and photophysical comparative analyses have been performed regarding the cyclometalated Pt(Naph^E) motif.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Cyclometalated Ligand Motifs on the Solid-State Assemblies and Luminescent Properties of Pt(II)-Tl(I) Complexes

et al. 2019

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We have synthesized the HC^Npz ligand, 1-(naphthalen-2-yl)-1H-pyrazole (1A), and carried out its cyclometalation reaction with [{Pt(η3-C4H7)(μ-Cl)}2] to give [{Pt(Naph^N)(μ-Cl)}2]. This process takes place via the intermediate [Pt(η3-C4H7)Cl(HNaph^N-κN)] (2A) which could be isolated and fully characterized. Compound [{Pt(Naph^N)(μ-Cl)}2] and the analogous N-heterocyclic carbene complex [{Pt(Naph^C*)(μ-Cl)}2] (HNaph^C*-κC* = 3-methyl-1-(naphthalen-2-yl)-1H-imidazol-2-ylidene) were used to prepare the bis-cyanide anionic derivatives N n Bu4[Pt(Naph^E)(CN)2] (E = Npz 4A, C*carbene 4B) which subsequently react with TlPF6 to afford the corresponding complexes [PtTl(Naph^E)(CN)2] (5A and 5B). The X-ray structures of 5A and 5B show the presence of 2D extended networks created by organometallic “PtTl(Naph^E)(CN)2” entities, each one containing a Pt→Tl dative bond (d Pt–Tl = 3.0205(3) Å 5A, 2.9395(4) Å 5B). These units are linked together through additional Tl···NC and Tl···π contacts, which, in the case of 5B, renders a stair-like arrangement. NBO charge distributions analysis on 4A and 4B shows a small negative charge on the Pt center for 4B, while positive for 4A, indicating the more electron donating character of the carbene with respect to the pyrazole group. 195Pt and 13C NMR spectra of N n Bu4[Pt(Naph^E)(13CN)2] (E = Npz 4A′, C*carbene 4B′) account for this difference. Photophysical analysis has been performed for 4A/B and 5A/B regarding the Naph^E fragment. The emissions of 4A and 4B in CH2Cl2 at 77 K present similar profiles and have been assigned to 3ILCT [π(Naph^E) → π*(Naph^E)] excited states. The green emission of 4A in poly(methyl methacrylate) (PMMA) film (5 wt %) affords a photoluminescence quantum yield (PLQY, Φ) of 82%. In the solid state, the vibronic emissions of 5A (λmax = 528 nm) and 5B (λmax = 561 nm) are red-shifted in relation to their precursors (λmax = 488 nm 4A, 530 nm 4B) and are mainly attributed to 3MM′LCT [d/s σ*(Pt,Tl) → π*(Naph^E)] excited states.

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Synthesis and Luminescent Properties of Zwitterionic Platinum Bis‐Phosphine Complexes Based on a Pendant Closo‐Monocarborane Cluster

Jin,

Shen,

Qiu

et al. 2024

Applied Organom Chemis

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The synthesis, structures and photophysical properties of a series of zwitterionic platinum complexes are reported. These cyclometalated complexes have the general structure Pt(C^N)(P^P), where C^N is a cyclometalating ligand with a pendant monocarborane cluster and P^P is a bis‐phosphine ligand (dppe or dppb). Their solid‐state structures have been characterized by x‐ray diffraction, and no Pt–Pt interactions are observed. All complexes are emissive at room temperature in solid states with quantum yields of 0.06–0.58 in PMMA films. The emission energy of these complexes is governed by the nature of the C^N cyclometalated ligands, allowing the emission to be tuned from blue to green. In particular, the introduction of an anionic carborane unit provokes a more than twofold improvement in the photoluminescence quantum yield of [Pt(CB11‐ppy)(dppe)] (3b) compared to the parent cationic complex [Pt(ppy)(dppe)]+. In addition, density functional theory (DFT) calculations were performed on the ground states and first triplet excited states of 1a, 2a, and 3a for interpretation of the observed photophysical properties.

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Highly efficient platinum-based emitters for warm white light emitting diodes

Abstract: The new compounds [Pt(R-C^C*)(P^P)]PF6 as blue or orange emitters were combined with the red emitter [Pt(bzq)(CN)(CNXyl)] to fabricate two-component WOLEDs and pcWLEDs. They rendered warm white light with optimal CRI and Duv values and a great range of nominal CCT: 4000 K–2000 K.

Cited by 14 publications

References 46 publications

Cyclometalated NHCs Pt(II) Compounds with Chelating P^P and S^S Ligands: From Blue to White Luminescence

Cyclometalated NHCs Pt(II) Compounds with Chelating P^P and S^S Ligands: From Blue to White Luminescence

The Influence of Cyclometalated Ligand Motifs on the Solid-State Assemblies and Luminescent Properties of Pt(II)-Tl(I) Complexes

Synthesis and Luminescent Properties of Zwitterionic Platinum Bis‐Phosphine Complexes Based on a Pendant Closo‐Monocarborane Cluster

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