Positive isotope effect in thermally activated delayed fluorescence emitters based on deuterium-substituted donor units

Cheng, Jin-Feng; Kong, Fan‐Cheng; Zhang, Kai; Cai, Jia-Heng; Zhao, Yue; Wang, Chuan‐Kui; Fan, Jian; Liao, Liang‐Sheng

doi:10.1016/j.cej.2021.132822

Cited by 31 publications

(25 citation statements)

References 47 publications

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“…Under 298 K, deuteration of ligands (NH 3 to ND 3 ) doubled the population decay lifetime in acidic aqueous solution . In addition, several studies pointed out that isotope effects are not limited to transition-metal complexes. − For example, Shibasaki et al studied the relaxation dynamic of perylene excimer in toluene, which shows a suppression of k IC of ∼15% for per-deuterated excimer in comparison to the parent perylene . Simpson et al demonstrated that both the numbers and positions of symmetrically arranged deuterium atoms on biphenyl significantly influence triplet lifetimes .…”

Section: Deuterium Isotope Effect and Relationship To Internal Conver...mentioning

confidence: 99%

Efficient Near-Infrared Luminescence of Self-Assembled Platinum(II) Complexes: From Fundamentals to Applications

et al. 2023

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Conspectus Designing bright and efficient near-infrared (NIR) emitters has drawn much attention due to numerous applications ranging from biological imaging, medical therapy, optical communication, and night-vision devices. However, polyatomic organic and organometallic molecules with energy gaps close to the deep red and NIR regime are subject to dominant nonradiative internal conversion (IC) processes, which drastically reduces the emission intensity and exciton diffusion length of organic materials and hence hampers the optoelectronic performances. To suppress nonradiative IC rates, we suggested two complementary approaches to solve the issues: exciton delocalization and molecular deuteration. First, exciton delocalization efficiently suppresses the molecular reorganization energy through partitioning to all aggregated molecules. According to the IC theory together with the effect of exciton delocalization, the simulated nonradiative rates with the energy gap ΔE = 104 cm–1 decrease by around 104 fold when the exciton delocalization length equals 5 (promoting vibronic frequency ω l = 1500 cm–1). Second, molecular deuterations reduce Franck–Condon vibrational overlaps and vibrational frequencies of promoting modes, which decreases IC rates by 1 order of magnitude in comparison to the rates of nondeuterated molecules under ΔE of 104 cm–1. Although deuteration of molecules has long been attempted to increase emission intensity, the results have been mixed. Here, we provide a robust derivation of the IC theory to demonstrate its validity, especially to emission in the NIR region. The concepts are experimentally verified by the strategic design and synthesis of a class of square-planar Pt(II) complexes, which form crystalline aggregates in vapor deposited thin films. The packing geometries are well characterized by the grazing angle X-ray diffraction (GIXD), showing domino-like packing arrangements with the short ππ separation of 3.4–3.7 Å. Upon photoexcitation, such closely packed assemblies exhibit intense NIR emission maximized in the 740–970 nm region through metal–metal-to-ligand charge transfer (MMLCT) transition with unprecedented photoluminescent quantum yield (PLQY) of 8–82%. To validate the existence of exciton delocalization, we applied time-resolved step-scan Fourier transform UV–vis spectroscopy to probe the exciton delocalization length of Pt(II) aggregates, which is 5–9 molecules (2.1–4.5 nm) assuming that excitons mainly delocalized along the direction of ππ stacking. According to the dependence of delocalization length vs simulated IC rates, we verify that the observed delocalization lengths contribute to the high NIR PLQY of the aggregated Pt(II) complexes. To probe the isotope effect, both partially and completely deuterated Pt(II) complexes were synthesized. For the case of the 970 nm Pt(II) emitter, the vapor deposited films of per-deuterated Pt(II) complexes exhibit the same emission peak as that of the nondeuterated one, whereas PLQY increases ∼50%. To put the fundamental studies into practi...

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Section: Deuterium Isotope Effect and Relationship To Internal Conver...mentioning

confidence: 99%

Efficient Near-Infrared Luminescence of Self-Assembled Platinum(II) Complexes: From Fundamentals to Applications

et al. 2023

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“…4(f) . 52 By employing the new electron donor based on tetraphenylethylene (TPE) triphenylamine, CAT-TPE ( Scheme 2 ) realized good solubility and aggregation induced emission behavior. As the first solution-processable NIR TADF molecule based on a fused polycyclic aromatic electron acceptor, TPE-CAT provided a new horizon for NIR TADF emitters.…”

Section: Pyrazine Derivatives With a Single Donormentioning

confidence: 99%

NIR TADF emitters and OLEDs: challenges, progress, and perspectives

et al. 2022

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“…39-43), and their emission was also confirmed to be fluorescence, as evidenced by their emission lifetimes (Supplementary Figs. [44][45][46]. Their microscopic morphologies were measured via SEM to determine the difference among resultant polymeric films at different reaction times.…”

Section: Interfacial Polymerization-induced Emission (Ipie) An Intere...mentioning

confidence: 99%

“…Notably, the isotope effect of traditional luminogens always results in enhanced PLQY but unchanged emission wavelength, [44][45][46][47][48][49] -5d). Therefore, EE-OBBO shows stronger intermolecular TSI than EE-DMODA.…”

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confidence: 99%

Facile Conversion of Water to Functional Molecules and Interfacial Polymers with Efficient Clusteroluminescence

Song

Zhang

Zhou

et al. 2023

Preprint

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Water is always used by nature to construct complex species. Learning from nature, the exploration of artificial approaches to utilize abundant water to synthesize functional molecules and polymers with efficient clusteroluminescence properties (CLgens) is highly significant but has yet to be reported. Herein, a new chemistry of water and alkyne was developed. The synthesized products were proved as nonaromatic CLgens that could emit visible light. Their emission colors and luminescent efficiency could be adjusted by manipulating through-space interaction via using different water and alkyne. Besides, the free-standing polymeric films with much high photoluminescence quantum yields (up to 45.7%) were in situ generated via a new H2O-involved interfacial polymerization. The interfacial polymerization-induced emission of the polymeric films was observed, where the emission red-shifted and efficiency increased when the polymerization time was prolonged. The synthesized polymeric film was also verified as a "Janus film". It exhibits a vapor-triggered reversible mechanical response which could be applied as a smart actuator. Thus, this work develops a new method to synthesize CLgens using water, builds a clear structure-property relationship of CLgens, and provides a novel strategy to in situ construct functional H2O-based polymeric films.

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Positive isotope effect in thermally activated delayed fluorescence emitters based on deuterium-substituted donor units

Cited by 31 publications

References 47 publications

Efficient Near-Infrared Luminescence of Self-Assembled Platinum(II) Complexes: From Fundamentals to Applications

Efficient Near-Infrared Luminescence of Self-Assembled Platinum(II) Complexes: From Fundamentals to Applications

NIR TADF emitters and OLEDs: challenges, progress, and perspectives

Facile Conversion of Water to Functional Molecules and Interfacial Polymers with Efficient Clusteroluminescence

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