Aggregation-induced emission triggered by the radiative-transition-switch of a cyclometallated Pt(<scp>ii</scp>) complex

Sun, Yi-Sui; Yang, Xiaolong; Liu, Boao; Guo, Haoran; Zhou, Guijiang; Ma, Wei; Wu, Zhaoxin

doi:10.1039/c9tc03838h

Cited by 33 publications

(16 citation statements)

References 54 publications

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“…The thermal gravimetric analysis revealed that the decomposition temperatures (T d ) of PyDPt, PmDPt, ThDPt, and QuDPt were 327, 273, 318, and 292 °C, respectively (Figure S4). At present, it is unclear why the pyrimidine-based dinuclear Pt(II) complex PmDPt had a slightly lower decomposition temperature, but this phenomenon is consistent with that recorded for corresponding mononuclear Pt(II) complexes (DPA-Pt: 43 T d = 263 °C; Pt-Py: 44 T d = 290 °C). Nevertheless, PyDPt, ThDPt, and QuDPt showed high T d close to or higher than 300 °C, indicating their good thermal stabilities.…”

Section: Resultssupporting

confidence: 75%

“…Compared with the PLQYs of the triphenylamine-based mononuclear Pt(II) complexes Pt-Py (PLQY = 0.07) 44 and DPA-Pt (PLQY = 0.03) 43 in CH 2 Cl 2 at room temperature, the PLQYs of these dinuclear Pt(II) complexes notably increased to 0.11−0.22. The improvement of emission efficiencies was temporarily attributed to the enhanced ISC due to the incorporation of the second Pt center.…”

Section: Resultsmentioning

confidence: 94%

“…The high-energy emissions were assigned to fluorescence because their lifetimes were only a few nanoseconds (Table ), while the low-energy emissions belonged to phosphorescence because of their much longer lifetimes from 0.13 to 0.32 μs. Because the electron-rich triphenylamine group usually makes a significant contribution to the highest occupied molecular orbitals (HOMOs) of Pt(II) complexes, which will reduce the contribution from the Pt center to HOMOs and weaken the spin–orbit interaction, thus it is a common phenomenon that the triphenylamine-based Pt(II) complexes can display both fluorescence and phosphorescence in solutions. ,,, By calculating the integrated area of the phosphorescence bands, the components of phosphorescence in the total luminescence were ca. 53.1, 80.1, 43.5, and 94.8% for PyDPt , PmDPt , ThDPt , and QuDPt , respectively.…”

Section: Resultsmentioning

confidence: 99%

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Developing Efficient Dinuclear Pt(II) Complexes Based on the Triphenylamine Core for High-Efficiency Solution-Processed OLEDs

Sun

Liu

Guo

et al. 2021

ACS Appl. Mater. Interfaces

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The various applications of dinuclear complexes have attracted increasing attention. However, the electroluminescence efficiencies of dinuclear Pt(II) complexes are far from satisfactory. Herein, based on the triphenylamine core, we develop four dinuclear Pt(II) complexes that cover the emission colors from yellow to red with high photoluminescence quantum efficiencies of up to 0.79 in doped films. The solid-state structure of PyDPt is revealed by the single-crystal X-ray diffraction investigation. Besides, solution-processed OLEDs have been fabricated with different electron transport materials. With higher electron mobility and excellent hole-blocking ability, 1,3,5-tri(m-pyridin-3-ylphenyl)benzene (TmPyPB) can help to realize good charge balance in related OLEDs. In addition, angle-dependent PL spectra reveal the preferentially horizontal orientation of these dinuclear Pt(II) complexes in doped CBP films, which benefits the outcoupling efficiencies. Therefore, the yellow OLED based on PyDPt shows unexpected high performance with a peak current efficiency of up to 78.7 cd/A and an external quantum efficiency of up to 22.4%, which is the highest EQE reported for OLEDs based on dinuclear Pt(II) complexes so far. This study demonstrates the great potential of developing dinuclear Pt(II) complexes for achieving excellent electroluminescence efficiencies.

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

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Developing Efficient Dinuclear Pt(II) Complexes Based on the Triphenylamine Core for High-Efficiency Solution-Processed OLEDs

Sun

Liu

Guo

et al. 2021

ACS Appl. Mater. Interfaces

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“…Since the pioneering report by Tang and co-workers, molecular materials with aggregation-induced or enhanced emissions (AIE or AEE) have aroused widespread interest. , Most of the current works focus on luminescent AIE/AEE materials. Purely organic chromophores or transitional metal complexes, including platinum complexes, have been documented to show aggregation-induced or -enhanced phosphorescent emission (AIPE or AEPE) with potential applications in light-emitting devices, information encryption, and bioimaging. − However, the scope of AIPE/AEPE materials remains to be expanded.…”

Section: Introductionmentioning

confidence: 99%

A Carbazole-Bridged Biscyclometalated Diplatinum Complex: Synthesis, Characterization, and Dual-Mode Aggregation-Enhanced Phosphorescence

2021

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A cationic carbazole-bridged biscyclometalated diplatinum complex 4 has been synthesized and characterized. Single-crystal X-ray analysis demonstrates that complex 4 displays a dimeric structure with noncovalent π–π stacking and unique double Pt–Pt interactions. In aerated dilute CH3CN, complex 4 is characterized by a very weak monomeric yellow emission (λemi = 547 nm; Φ = 0.51%), which is attributed to the triplet intraligand (3LC) excited state mixing with some charge transfer characters. In contrast, under aerated conditions, the dispersion of 4 in a mixed solvent of CH3CN/Et2O (1/9, v/v) or CH3CN/H2O (1/9, v/v) displays intense yellow (λemi = 550 nm; Φ = 35.5%; τ = 11.10 μs) and red emission (λemi = 635 nm; Φ = 14.1%; τ = 7.00 μs), respectively. These aggregation-induced phosphorescent emission enhancements are considered being caused by the oxygen-shielding effect and the molecular rigidification-induced decrease of nonradiative decays in the aggregate state. The morphology and size of the aggregates under these two conditions are examined by scanning electron microscope and dynamic light scattering analysis. The absorption and emission properties of 4 are further rationalized by time-dependent density functional theory calculations on a model compound.

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“…Molecules are individual building blocks, and the way in which they organize has a great impact on their chemical and physical properties. Based on the interacting molecules, cation−π interactions, − anion−π interactions, − lone pair interactions, CH···π interactions, π–π stacking interactions, , and metallophilic interactions − have emerged as driving intermolecular forces in aggregated structures. In other scenarios, nondirectional hydrophobic (i.e., dispersion-driven) interactions drive the formation of molecular aggregates .…”

Section: Introductionmentioning

confidence: 99%

Formation of Excimers in Isoquinolinyl Pyrazolate Pt(II) Complexes: Role of Cooperativity Effects

et al. 2020

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The interplay between noncovalent interactions involving metal complexes may lead to the formation of aggregates (i.e., ground state dimers, trimers, n-mers, etc.), and this is often linked to dramatic changes in their physical and chemical properties as compared to the original properties of the isolated units. Dimers and trimers can also be formed in the excited state potential energy surfaces, i.e., excimers. Excimers are short-lived but are also often characterized by different optical properties from those of the isolated units. Understanding the nature of noncovalent interactions and the presence or not of cooperativity effects in both aggregates and excimers is thus extremely important to rationalize these variations. In this study, we present computational investigations on isoquinolinyl pyrazolate Pt(II) complexes. Our results highlight that cooperativity effects between noncovalent interactions, which are modulated by sterically demanding substituents and metallophilic Pt•••Pt interactions, are present only on certain investigated excimers. We use density functional theory (DFT) calculations to examine the cooperativity effects and the changes in the photophysical properties. Different descriptors of cooperativity effects between noncovalent interactions, including the synergetic, genuine nonadditive, and total interaction energies, were evaluated for a series of Pt(II) aggregates and excimers. In addition, energy decomposition analysis (EDA) calculations were performed to rationalize the origins of the cooperative effects. The cooperative effects in trimer excimers (in their lowest triplet excited state, i.e., T 1 ) led to shortened Pt••• Pt contacts as compared to the trimer aggregates. Furthermore, this synergy between noncovalent interactions is ultimately responsible for the formation of the excimers and the striking changes in the measured photophysical properties. More in detail, we report a change in the character of the lowest-lying triplet excited state when going from dimer excimers (i.e., of mixed triplet ligandcentered and triplet metal-to-ligand charge transfer ( 3 LC/ 3 MLCT) character) to trimer excimers (i.e., of triplet metal−metal-toligand charge transfer ( 3 MMLCT) character). The EDA reveals that the total interaction energy on trimer excimers is subtly controlled by the electrostatic and dispersion terms.

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Aggregation-induced emission triggered by the radiative-transition-switch of a cyclometallated Pt(ii) complex

Abstract: A new mechanism, namely radiative transition switch (RTS), has been proposed for aggregation-induced emission, which is of importance for developing highly efficient AIE-active emitters.

Cited by 33 publications

References 54 publications

Developing Efficient Dinuclear Pt(II) Complexes Based on the Triphenylamine Core for High-Efficiency Solution-Processed OLEDs

Developing Efficient Dinuclear Pt(II) Complexes Based on the Triphenylamine Core for High-Efficiency Solution-Processed OLEDs

A Carbazole-Bridged Biscyclometalated Diplatinum Complex: Synthesis, Characterization, and Dual-Mode Aggregation-Enhanced Phosphorescence

Formation of Excimers in Isoquinolinyl Pyrazolate Pt(II) Complexes: Role of Cooperativity Effects

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