Polyatomic molecules with emission quantum yields &gt;20% enable efficient organic light-emitting diodes in the NIR(II) window

Wang, Shengfu; Su, Borching; Wang, Xueqi; Wei, Yu‐Chen; Kuo, Kai‐Hua; Wang, Chih-Hsing; Liu, Shih-Hung; Liao, Liang‐Sheng; Hung, Wen‐Yi; Fu, Li-Wen; Chuang, Wei‐Tsung; Qin, Minchao; Lu, Xinhui; You, Caifa; Chi, Yun; Chou, Pi‐Tai

doi:10.1038/s41566-022-01079-8

Cited by 93 publications

(59 citation statements)

References 46 publications

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“…This, together with the direct involvement of metal−ligand interaction leads to ultrafast intersystem crossing and hence the unitary population of the lowest lying triplet complexes thus manifest a bathochromic shift to 920−970 nm with a PLQY of 13−16%. 4 After partial or completed deuteration of these complexes, PLQY can be further enhanced to 19−26%. Finally, the NIR OLED device reaches an EL peak wavelength of 995 nm with a maximum EQE of 4.31% and an operational radiance of >10 W sr −1 m −2 , setting up a landmark on the history of NIR OLEDs.…”

Section: Introductionmentioning

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: Introductionmentioning

confidence: 99%

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

et al. 2023

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“…In this context, aggregation of Pt( ii ) complexes driven by intermolecular Pt–Pt and π–π interactions have been comprehensively explored which are pioneered by Chi and co-workers. 7 It has been well established that the metallophilic interactions can generate triplet metal–metal-to-ligand charge transfer ( 3 MMLCT) excited states which are typically characterized by high radiative decay rates. 8 Further, in comparison with their mononuclear analogues, the emission energies of 3 MMLCT excited states are significantly smaller.…”

Section: Introductionmentioning

confidence: 99%

High-efficiency and stable red to near-infrared organic light-emitting diodes using dinuclear platinum(ii) complexes

Wang

Wen

et al. 2023

Mater. Chem. Front.

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“…This, together with the phosphorescence nature of the Pt(II) complexes, sets up a milestone in fabricating the NIR organic light-emitting diodes (OLEDs) spanning from the NIR(I) 12,13 to NIR(II) region. 14 However, the prerequisite of ordered self-assembly via vapor deposition or crystallization hampers their application in bioimaging and biosensing; particularly, biomedical applications demand targeting specificity. Therefore, the quest for emissive organic dyes in the NIR(II) region, which can be modified via bioconjugation, is a top priority in the current research trend.…”

Section: ■ Introductionmentioning

confidence: 99%

“…As a result, the extended exciton delocalization not only reduces the emission gap to the NIR(II) region but also disperses the molecular vibrational displacement induced by electronic excitation, making the displacement relevant vibrations shorter, which can be viewed as reducing the electronic–vibrational coupling and hence suppressing internal reorganization energy λ. This, together with the phosphorescence nature of the Pt(II) complexes, sets up a milestone in fabricating the NIR organic light-emitting diodes (OLEDs) spanning from the NIR(I) , to NIR(II) region . However, the prerequisite of ordered self-assembly via vapor deposition or crystallization hampers their application in bioimaging and biosensing; particularly, biomedical applications demand targeting specificity.…”

Section: Introductionmentioning

confidence: 99%

Rational Design of Asymmetric Polymethines to Attain NIR(II) Bioimaging at >1100 nm

Pan

Lin

et al. 2022

J. Am. Chem. Soc.

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Organic molecules having emission in the NIR(II) region are emergent and receiving enormous attention. Unfortunately, attaining accountable organic emission intensity around the NIR(II) region is hampered by the dominant internal conversion operated by the energy gap law, where the emission energy gap and the associated internal reorganization energy λ int play key roles. Up to the current stage, the majority of the reported organic NIR(II) emitters belong to those polymethines terminated by two symmetric chromophores. Such a design has proved to have a small λ int that greatly suppresses the internal conversion. However, the imposition of symmetric chromophores is stringent, limiting further development of organic NIR(II) dyes in diversity and versatility. Here, we propose a new concept where as far as the emissive state of the any asymmetric polymethines contains more or less equally transition density between two terminated chromophores, λ int can be as small as that of the symmetric polymethines. To prove the concept, we synthesize a series of new polymethines terminated by xanthen-9-yl-benzoic acid and 2,4-diphenylthiopyrylium derivatives, yielding AJBF1112 and AEBF1119 that reveal emission peak wavelength at 1112 and 1119 nm, respectively. The quantum yield is higher than all synthesized symmetric polymethines of 2,4-diphenylthiopyrylium derivatives (SC1162, 1182(SC1162, , 1185(SC1162, , and 1230) in this study. λ int were calculated to be as small as 6.2 and 7.3 kcal/mol for AJBF1112 and AEBF1119, respectively, proving the concept. AEBF1119 was further prepared as a polymer dot to demonstrate its in vitro specific cellular imaging and in vivo tumor/bone targeting in the NIR(II) region.

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Polyatomic molecules with emission quantum yields >20% enable efficient organic light-emitting diodes in the NIR(II) window

Cited by 93 publications

References 46 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

High-efficiency and stable red to near-infrared organic light-emitting diodes using dinuclear platinum(ii) complexes

Rational Design of Asymmetric Polymethines to Attain NIR(II) Bioimaging at >1100 nm

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