High efficiency pure blue thermally activated delayed fluorescence molecules having 10H-phenoxaborin and acridan units

Numata, Masaki; Yasuda, Takuma; Adachi, Chihaya

doi:10.1039/c5cc00307e

Cited by 298 publications

(231 citation statements)

References 22 publications

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“…Interestingly, triarylboron derivatives have often been opposed to donors, such as 9,10-dihydroacridine, triphenylamine of the popular carbazole group [91][92][93]. Some of them even show CIE coordinates of (0.15, 0.09) and (0.15, 0.08) for the PL of emitters in toluene but none of them gave OLEDs with colour coordinates satisfying or being close to the NTSC blue standard of CIE coordinates (0.14, 0.08) [94]. Recently, Hatakeyama et al reported a new strategy to design effective deep blue triarylboron based emitters [95].…”

Section: Triarylborane Emittersmentioning

confidence: 99%

Thermally Activated Delayed Fluorescence Emitters for Deep Blue Organic Light Emitting Diodes: A Review of Recent Advances

et al. 2018

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Organic light-emitting diodes offer attractive perspectives for the next generation display and lighting technologies. The potential is huge and the list of potential applications is almost endless. So far, blue emitters still suffer from noticeably inferior electroluminescence performances in terms of efficiency, lifespan, color quality, and charge injection/transport when compared to that of the other colors. Emitting materials matching the NTSC standard blue of coordinates (0.14, 0.08) are extremely rare and still constitutes the focus of numerous academic and industrial researches. In this context, we review herein the recent developments on highly emissive deep-blue thermally activated delayed fluorescence emitters that constitute the third-generation electroluminescent materials.

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Section: Triarylborane Emittersmentioning

confidence: 99%

Thermally Activated Delayed Fluorescence Emitters for Deep Blue Organic Light Emitting Diodes: A Review of Recent Advances

et al. 2018

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“…17,22 Such subvertical D-A structure can suppress the conjugation between D and A segments, and strictly isolate the HOMO and LUMO orbitals on D and A segments, respectively. [17][18][19][20]22 Till now, nearly all of the reported TADF emitters are based on such design strategy, and successfully exhibit high efficiencies in the devices. However, without the restriction from the conjugation between D and A segments, the structural relaxations of TADF emitters become evident, resulting in increased Stokes shift and broadened emission spectra.…”

Section: Introductionmentioning

confidence: 99%

“…32 Thus, it is impossible to realize high efficiencies in OLED displays with current TADF emitters. 17,[29][30][31][32] Most recently, Hatakeyama and his co-workers successfully utilized the multiple resonance effect to construct TADF emitters with extremely narrow FWHM. 32 However, this strategy is strictly confined to specific molecular structure and inapplicable for current D-A structure TADF emitters; and the OLEDs based on their new TADF emitters suffer serious efficiency roll-off and extremely low maximum luminance of about 200 cd m -2 .…”

Section: Introductionmentioning

confidence: 99%

“…18-21 3 To realize the key point of extremely small ∆E ST s for TADF emitters, minimizing the overlap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) in the molecules is essential. 15,[17][18][19][20] Thus, TADF emitters are generally constructed by linking the electron-donor (D) segment and electron-acceptor (A) segment with a nearly vertical dihedral angle. 17,22 Such subvertical D-A structure can suppress the conjugation between D and A segments, and strictly isolate the HOMO and LUMO orbitals on D and A segments, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Isomeric Thermally Activated Delayed Fluorescence Emitters for Color Purity-Improved Emission in Organic Light-Emitting Devices

Chen

Liu

Zheng

et al. 2016

ACS Appl. Mater. Interfaces

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To improve the color purity of TADF emitters, two isomeric compounds, oPTC (5'-(phenoxazin-10-yl)-[1,1':3',1''-terphenyl]-2'-carbonitrile) and mPTC (2'-(phenoxazin-10-yl)-[1,1':3',1''-terphenyl]-5'-carbonitrile), have been designed and synthesized with same skeleton but different molecular restrictions. Both two compounds exhibit similar HOMO, LUMO distributions and energy levels, photophysical properties in nonpolar cyclohexane solution, and high external quantum efficiencies (19.9% for oPTC and 17.4% for mPTC) in the devices. With the increased molecular space restriction induced by the additional phenyl substitutions at meta-position of the cyano-group from mPTC to oPTC, much weaker positive solvatochromic effect is observed for mPTC. And the color purity of emission from mPTC (FWHM of 86 nm) is alsoimproved contrasted with that of oPTC (FWHM of 97 nm) in the devices. These results prove that increased restriction of the molecular structure is a simple and effective method to improve the color purity of the TADF emitters.

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“…[19][20][21][22][23] However, these OLEDs can only utilize singlet excitons for electroluminescence (EL) and the resulting internal EL quantum efficiency (η int ) is limited to 25% because of the inherent spin-statistical limitation of electrical excitation, which generates radiative singlet excitons and non-radiative triplet excitons in a 1:3 ratio. 24 Recent research efforts in our group 25 and others [26][27][28][29][30] have focused on exploring AIE-active materials that simultaneously exhibit thermally activated delayed florescence [31][32][33][34][35][36][37][38][39] to harvest triplet excitons for EL via efficient reverse intersystem crossing. To expand the library of such unique fluorophores that display aggregation-induced delayed fluorescence (AIDF), we report on two yellow AIDF materials, PTZ-XT and PTZ-BP ( Figure 1) that consist of an electron-donating phenothiazine unit coupled with an electron-accepting xanthone or benzophenone unit.…”

Section: Introductionmentioning

confidence: 99%

Aggregation-induced delayed fluorescence from phenothiazine-containing donor–acceptor molecules for high-efficiency non-doped organic light-emitting diodes

Aizawa

Tsou

Park

et al. 2016

Polym J

Self Cite

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Highly luminescent donor-acceptor molecules based on a phenothiazine donor unit coupled with a xanthone or benzophenone acceptor unit were developed for use in organic light-emitting diodes (OLEDs). While both molecules are almost non-luminescent in pure tetrahydrofuran (THF) solution, a strong yellow delayed fluorescence was observed upon their aggregation in THF/water mixtures or in neat films. This result demonstrates the unique aggregation-induced delayed fluorescence (AIDF) characteristics of these molecules. OLEDs using these AIDF materials as a non-doped emission layer achieved high external electroluminescence quantum efficiencies of up to 11%, which exceeds the theoretical maximum for conventional fluorescent OLEDs. Polymer Journal ( INTRODUCTION Solid-state organic fluorophores have been actively explored for various optoelectronic applications, in particular for organic lightemitting diodes (OLEDs). 1 Although most organic fluorophores are highly luminescent in dilute solutions, their luminescence is generally weakened or quenched in the solid state via bimolecular recombination and energy transfer to non-luminescent impurities, which results in a substantial energy loss in the OLEDs. [2][3][4][5] This problem is typically circumvented by dispersing the fluorophores in wide bandgap host materials via precise co-evaporation processes; however, this approach requires complex manufacturing procedures. Thus, highly luminescent solid-state fluorophores are highly desirable for simplifying the device structure and the fabrication process.In 2001, Tang and co-workers 6,7 identified materials that exhibit aggregation-induced emission (AIE). In contrast to conventional fluorophores, these AIE-active fluorophores are almost nonluminescent in dilute solutions, yet they become highly luminescent upon molecular aggregation. This AIE phenomenon can be explained by the restriction of non-radiative vibrational relaxation processes in the aggregated solid state. Representative examples of AIE-active fluorophores include siloles, 6-9 cyanostilbenes, 10-12 o-carborane derivatives 13-17 and tetraphenylethenes [18][19][20][21][22][23] . Some of these fluorophores have proved useful as non-doped emission layers in fluorescent OLEDs. [19][20][21][22][23] However, these OLEDs can only utilize singlet excitons for electroluminescence (EL) and the resulting internal EL quantum efficiency (η int ) is limited to 25% because of the inherent spin-statistical limitation of electrical excitation, which

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High efficiency pure blue thermally activated delayed fluorescence molecules having 10H-phenoxaborin and acridan units

Abstract: Highly efficient blue thermally activated delayed fluorescence molecules having 10H-phenoxaborin and acridan units were reported. Pure blue emission peaking at around 450 nm with a high external electroluminescence quantum efficiency of around 20% was demonstrated.

Cited by 298 publications

References 22 publications

Thermally Activated Delayed Fluorescence Emitters for Deep Blue Organic Light Emitting Diodes: A Review of Recent Advances

Thermally Activated Delayed Fluorescence Emitters for Deep Blue Organic Light Emitting Diodes: A Review of Recent Advances

Isomeric Thermally Activated Delayed Fluorescence Emitters for Color Purity-Improved Emission in Organic Light-Emitting Devices

Aggregation-induced delayed fluorescence from phenothiazine-containing donor–acceptor molecules for high-efficiency non-doped organic light-emitting diodes

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