Highly efficient nondoped blue organic light-emitting diodes with high brightness and negligible efficiency roll-off based on anthracene-triazine derivatives

Liu, Futong; Man, Xiaxia; Liu, Hui; Min, Jiarui; Zhao, Shiyuan; Min, Wenrong; Gao, Lei; Jin, Haixu; Lü, Ping

doi:10.1039/c9tc05040j

Cited by 41 publications

(26 citation statements)

References 51 publications

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“…High-energy HLCT states T 3 and T 4 and small energy splitting between S 1 and T 3 or T 4 (ΔE ST = 0.09 and 0.08 eV, respectively) were observed, which might facilitate the reverse intersystem crossing (RISC) process and procure a high fluorescence radiation and EUE ratio in OLEDs. [41][42][43][44][45][46][47][48][49][50][51][52] Furthermore, it has been proved that introducing a π-conjugated phenyl ring unit between the D and A serves as an appropriate method for the effective modulation of HLCT excited state. 36…”

Section: Theoretical Calculationsmentioning

confidence: 99%

“…In recent years, materials with hybrid local and CT (HLCT) excited state were also well developed, which successfully achieved the merits of high η PL and a high output of singlet excitons in a series of donor (D)-acceptor (A) materials. 36,[41][42][43][44][45][46][47][48][49][50][51][52] HLCT materials also show the potential to maintain stable η ext at high brightness. Thus, there is still room for further enhancement of the η ext of blue OLEDs and low efficiency roll-offs in pyrene-based D-A system.…”

Section: Introductionmentioning

confidence: 99%

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Highly Efficient Blue Organic Light-Emitting Diode Based on a Pyrene[4,5- d ]Imidazole-Pyrene Molecule

et al. 2022

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Organic light-emitting diodes (OLEDs), which have been recently utilized in some flat-panel display screens such as mobile phones and televisions, show many merits, including light weight, high flexibility, energy preservation, and so forth, and are considered the next-generation displays and solid-state lightings. Blue-emitting materials that can be applied in nondoped OLEDs with little efficiency roll-offs at high brightness are of great importance. Here, a highly efficient, blue-emitting material, 9-phenyl-10-(4-(pyren-1-yl)phenyl)-9H-pyreno [4,5-d]imidazole (PyPI-Py), is achieved using pyrene [4,5-d]imidazole and pyrene as the weak electron donor and electron acceptor, respectively. The nondoped blue OLED exhibits excellent performance with a maximum brightness of 75,687 cd m −2 , a maximum current efficiency of 13.38 cd A −1 , and a maximum external quantum efficiency (η ext ) of 8.52%. Moreover, the η ext is maintained at 8.35% and 8.05% at a brightness of 10,000 and 50,000 cd m −2 , respectively, displaying extremely small efficiency roll-offs of 2.0% and 5.5%.The device characteristics are among the highest values for nondoped blue OLEDs and correspond to the best performance obtained for nondoped pyrene-based blue OLEDs. The superior performance is attributed to the proper donor-acceptor design strategy which results in a quasi-equivalent hybrid local and charge-transfer excited state with the maximum generation of an 82% fraction of singlet excitons.

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Section: Theoretical Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Highly Efficient Blue Organic Light-Emitting Diode Based on a Pyrene[4,5- d ]Imidazole-Pyrene Molecule

et al. 2022

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“…12,13 In comparison, the much short exciton lifetimes of HLCT emitters benefit to suppress exciton annihilation and thus improve efficiency roll-off. 14,15 Given the fact that the HLCT concept was proposed a few years ago, to date the development of HLCT emitters still lags behind TADF emitters. [16][17][18] In particular, device performances of most HLCT-based OLEDs remain restricted as their external quantum efficiencies (EQEs) are generally <10%, 10,15,[19][20][21][22][23] leaving much room for efficiency improvement.…”

Section: Introductionmentioning

confidence: 99%

Hybridized Local and Charge-Transfer Excited-State Fluorophores through the Regulation of the Donor–Acceptor Torsional Angle for Highly Efficient Organic Light-Emitting Diodes

Chen

Liu

et al. 2022

CCS Chem

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Hybridized local and charge-transfer (HLCT) excited-state fluorophores, which enable full exciton utilization through a reverse intersystem crossing from high-lying triplet states to singlet state, have attracted increasing attention toward organic light-emitting diodes (OLEDs) application. Herein, we report three D-π-A-π-D-type isomers o-2CzBT, m-2CzBT, and p-2CzBT by adjusting the donor (D) units from ortho-, meta-, to para-substituted positions with the acceptor (A) core unit, respectively. The HLCT properties of the three compounds are evidently confirmed by theoretical calculations, solvatochromic behaviors, and transient decay lifetimes analyses. As the substituted position changes from the ortho-, meta-, and para-positions, the reduced steric hindrance brings about decreased torsional angle between D and A moieties, resulting in increased oscillator strength. Accordingly, the para-substituted p-2CzBT is endowed with a more locally excited component that accounts for faster radiative decay, leading to a higher fluorescent efficiency than that of o-2CzBT and m-2CzBT. As expected, p-2CzBT enables its nondoped and doped OLEDs with higher external quantum efficiencies (EQEs) of 12.3% and 15.0%, respectively, which are among the state-of-the-art efficiencies of HLCT-based OLEDs. Moreover, o-2CzBT and m-2CzBT are also utilized as host materials for high-performance OLEDs, thus extending the application of HLCT materials.

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“…Thus, the corresponding radiative rate is calculated to be beyond 10 8 s −1 , illustrating that PHT‐PPI is a suitable candidate for OLED applications. [ 29 ] PHT‐PPI possesses first singlet energy level ( E S1 ) and E T1 of 3.09 and 2.44 eV, respectively, determined by the highest energy vibronic sub‐band of the fluorescence and phosphorescence spectra at 77 K (Figure S8, Supporting Information). And the high E T1 is conducive to the energy transfer from the host to the phosphors.…”

Section: Resultsmentioning

confidence: 99%

Effective Energy Transfer for Green, Orange, and Red Phosphorescent Organic Light‐Emitting Diodes Based on a Bipolar Deep‐Blue Emitter with Low Efficiency Roll‐Off at High Brightness

Yang

Zhu

Tang

et al. 2021

Advanced Photonics Research

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Of paramount significance in phosphorescent organic light‐emitting diodes (PHOLEDs) are the facts that Förster resonance energy transfer (FRET) must be sufficient and back energy transfer should be prohibited. Herein, the FRET efficiencies for high‐performance PHOLEDs based on a simple bipolar luminogen 1‐phenyl‐2‐(5′‐phenyl‐[1,1′:3′,1″‐terphenyl]‐4‐yl)‐1H‐phenanthro[9,10‐d]imidazole (PHT‐PPI) with high triplet energy of 2.44 eV are systematically investigated. As a result, with PO‐01 as dopant, the high‐performance orange PHOLED is achieved with maximum external quantum efficiency (EQEmax) of 26.14% and ultrahigh brightness of 152 000 cd m−2, which are the highest reported efficiencies for orange OLEDs with such high brightness. In addition, the green and red PHOLEDs are also fabricated with EQEmax of 15.38% and 16.12%, respectively. Furthermore, the nondoped device based on PHT‐PPI as a deep‐blue emitter is also obtained with an EQEmax of 5.12% and the Commission Internationale de L’Eclairage (CIE) index of (0.15, 0.08). More importantly, the blue, green, orange, and red devices exhibit low efficiency roll‐off, particularly, of which the orange PHOLED is extremely small (<9%) even at the brightness of 10 000 cd m−2.

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Highly efficient nondoped blue organic light-emitting diodes with high brightness and negligible efficiency roll-off based on anthracene-triazine derivatives

Abstract: A nondoped device based on the PIAnTAZ emitter shows blue electroluminescence with a maximum EQE of 7.96%, a maximum luminance of 58 675 cd m−2 and negligible efficiency roll-offs.

Cited by 41 publications

References 51 publications

Highly Efficient Blue Organic Light-Emitting Diode Based on a Pyrene[4,5- d ]Imidazole-Pyrene Molecule

Highly Efficient Blue Organic Light-Emitting Diode Based on a Pyrene[4,5- d ]Imidazole-Pyrene Molecule

Hybridized Local and Charge-Transfer Excited-State Fluorophores through the Regulation of the Donor–Acceptor Torsional Angle for Highly Efficient Organic Light-Emitting Diodes

Effective Energy Transfer for Green, Orange, and Red Phosphorescent Organic Light‐Emitting Diodes Based on a Bipolar Deep‐Blue Emitter with Low Efficiency Roll‐Off at High Brightness

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