Short‐Wavelength Infrared Organic Light‐Emitting Diodes from A–D–A′–D–A Type Small Molecules with Emission beyond 1100 nm

Liu, Wansheng; Deng, Suinan; Zhang, Lianjie; Ju, Cheng‐Wei; Xie, Yuan; Deng, Wanling; Chen, Junwu; Wu, Hongbin; Cao, Yong

doi:10.1002/adma.202302924

Cited by 8 publications

(1 citation statement)

References 54 publications

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“…In recent years, near-infrared (NIR) light-emitting materials have received great attention because of their many civilian and military applications, − such as infrared signaling, optical communications, night vision, information-secured displays, bioimaging, medical diagnostics, and biometric identification. − For practical applications of NIR-emissive materials, high quantum yield, excellent stability, and tunable properties are required. − A large variety of NIR-emissive materials have been reported, including organic small molecules, − organometallic complexes, − polymers, − carbon dots, − and semiconductor quantum dots. − Among them, conjugated polymers as NIR emitters have the advantages of tunable optoelectronic properties, flexibility, low cost, and excellent mechanic properties. − …”

Section: Introductionmentioning

confidence: 99%

Organoboron-Conjugated Homopolymers with Bright Narrowband Near-Infrared Emission

Gao,

Zhang,

Zhang

et al. 2024

Macromolecules

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Near-infrared (NIR) light-emitting polymers are important because of their many civilian and military applications. The general strategy to design NIRemissive conjugated polymers is to copolymerize an electron-donating unit and electron-accepting unit to design donor−acceptor-type copolymers. The resulting NIR-emissive copolymers suffer from low fluorescence efficiencies and wide fluorescence spectra. In this work, we report a series of organoboron-conjugated homopolymers with high quality NIR light emission. The repeating unit of these homopolymers is a double B←N-bridged bipyridine (BNBP) unit bearing diphenylether as a large steric hindrance. Because of the rigid backbone and small reorganization energy of BNBP, the organoboron homopolymers emit highquality NIR light with the emission peak wavelength of ca. 750 nm, fluorescence quantum efficiency of ca. 0.7, and full width at half-maximum of ca. 50 nm. The application of these homopolymers as visible to NIR light converters in NIR organic light-emitting diodes has been demonstrated. This work indicates a new strategy of organoboron chemistry to develop narrow-band and bright NIR-emissive polymers for practical applications.

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Section: Introductionmentioning

confidence: 99%

Organoboron-Conjugated Homopolymers with Bright Narrowband Near-Infrared Emission

Gao,

Zhang,

Zhang

et al. 2024

Macromolecules

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Efficient Near‐Infrared Organic Light‐Emitting Diodes with Emission Peak Above 900 nm Enabled by Enhanced Photoluminescence Quantum Yields and Out‐Coupling Efficiencies

An,

Deng,

Xie

et al. 2024

Adv Funct Materials

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Near‐infrared organic light‐emitting diodes (NIR OLEDs) with emission peak above 900 nm are attractive for many emerging applications, spanning from bioimaging to light detection and ranging. However, the device performance of NIR OLEDs is generally limited by the low quantum efficiency of emitters because of the fast nonradiative transition process imposed by energy‐gap law and aggregation quenching. So far, only a few Pt(II) complexes delivering external quantum efficiency (EQE) over 1% are reported, while there is no comparable electroluminescence in heavy‐metal‐free fluorescent organic emitters. Here, NIR OLEDs centered at 934 nm by blending an acceptor–donor–acceptor type molecule Y11 into a polymer host poly[(9,9‐dioctylfluorenyl‐2,7‐diyl)‐alt‐(4,4′‐(N‐(4‐sec‐butylphenyl)diphenylamine) (TFB) are reported. The OLEDs show a remarkably high EQE of 1.72%. Moreover, owing to a low turn‐on voltage (≈0.9 V), the resultant NIR OLEDs have an electricity‐to‐light power efficiency surpassing 20 mW W−1. The improved device performance can be attributed to enhanced photoluminescence quantum yields (PLQYs) of the blends owing to suppressed aggregation quenching, and favorable light extraction from the emissive layer. Such values are the highest among fluorescent OLEDs with electroluminescence above 900 nm.

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Thieno[3, 4‐b]thiadiazole Based Donor‐Acceptor Cyclic Oligomers: Ring Size‐Dependent Photophysical Properties and Efficient Near‐Infrared Electroluminescence Beyond 900 nm

Zhang,

Liu,

et al. 2024

Adv Funct Materials

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Organic donor‐acceptor (D‐A) conjugated macrocycles, which are regarded as terminal‐less counterparts of linear π‐systems, have emerged as a promising class material for organic optoelectronics. Nevertheless, circular symmetry generally makes the lowest electronic transition symmetry forbidden, which is a huge obstacle to developing bright near‐infrared macrocyclic dyes. Here, a series of cyclic D‐A oligomers (e.g., cyclic D‐A dimer ([2]C16TT‐TPA), trimer ([3]C16TT‐TPA), and tetramer ([4]C16TT‐TPA)) are synthesized in which triphenylamine and 4,6‐bisthienylthieno[3,4‐c]thiadiazole are alternately coupled. The ring size‐dependent photophysical properties of D‐A cyclic oligomers, such as photoluminescence quantum yield and radiative decay rate, are revealed through both experiments and theoretical calculations. Owing to conformational flexibility and dominant twisted conformation, [3]C16TT‐TPA shows increasing S0→S1 transition and thereby produces a champion photoluminescence quantum yield of 6.35 % in solution with emission beyond 900 nm, much higher than that of acyclic oligomer (1.56%). Furthermore, the [3]C16TT‐TPA‐based organic light‐emitting diode achieves a relatively high external quantum efficiency of 0.15% with a maximum radiance of 2897 mW sr−1 m−2. The study not only provides insights into the mechanism of ring size‐dependent photophysical properties but also demonstrates the potential of D–A cyclic oligomers for bright near‐infrared emitters.

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Short‐Wavelength Infrared Organic Light‐Emitting Diodes from A–D–A′–D–A Type Small Molecules with Emission beyond 1100 nm

Cited by 8 publications

References 54 publications

Organoboron-Conjugated Homopolymers with Bright Narrowband Near-Infrared Emission

Organoboron-Conjugated Homopolymers with Bright Narrowband Near-Infrared Emission

Efficient Near‐Infrared Organic Light‐Emitting Diodes with Emission Peak Above 900 nm Enabled by Enhanced Photoluminescence Quantum Yields and Out‐Coupling Efficiencies

Thieno[3, 4‐b]thiadiazole Based Donor‐Acceptor Cyclic Oligomers: Ring Size‐Dependent Photophysical Properties and Efficient Near‐Infrared Electroluminescence Beyond 900 nm

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