High-Efficiency Sky-Blue Organic Light-Emitting Diodes Utilizing Thermally-Activated Delayed Fluorescence

Hiraga, Yasuhide; Nishide, Jun Ichi; Nakanotani, Hajime; Aonuma, Masaki; Adachi, Chihaya

doi:10.1587/transele.e98.c.971

Cited by 8 publications

(4 citation statements)

References 23 publications

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“…To investigate electroluminescent (EL) properties of the proposed ortho D–A emitters, TADF-OLED devices were fabricated in two device configurations (type I for orange and greenish-blue devices and type II for blue devices; see Experimental Section and Figure S15 for full details). Orange (PXZ o B, E T = 2.44 eV) and greenish-blue (DPA o B, E T = 2.56 eV) emitters were doped into the exciplex-forming cohost system of N , N ′-dicarbazolyl-3,5-benzene (mCP, E T = 2.90 eV) and 4,6-bis[3,5-di-(pyridin-3-yl)phenyl]-2-methylpyrimidine (B3PyMPM, E T = 2.68 eV), in which a molar ratio of the mCP:B3PyMPM cohost ( E T = 2.97 eV) was 1:1. , Notably, the T 1 levels of PXZ o B and DPA o B are less than those of the adjacent layers and cohost, which ensures efficient exciton confinement and suppresses backward energy transfer. In the case of blue devices, the emitter (Cz o B, E T = 2.80 eV) was doped into a single-host system of bis[2-(diphenylphosphino)phenyl]ether oxide (DPEPO, E T = 3.30 eV) due to the high E T and band-gap energy of DPEPO. , …”

Section: Resultsmentioning

confidence: 99%

Rigidity-Induced Delayed Fluorescence by Ortho Donor-Appended Triarylboron Compounds: Record-High Efficiency in Pure Blue Fluorescent Organic Light-Emitting Diodes

Lee

Park

et al. 2017

ACS Appl. Mater. Interfaces

140

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A synthetic approach to highly efficient thermally activated delayed fluorescence (TADF) is proposed that uses ortho donor (D)-acceptor (A) compounds (PXZoB, DPAoB, and CzoB), wherein the acceptor is based on triarylboron and the donor is phenoxazine (PXZ), diphenylamine (DPA), or carbazole (Cz). Combined with the ortho D-A connectivity, the bulky nature of the triarylboron endows the D-A dyads with inherent steric "locking" for a highly twisted arrangement, leading to a small energy difference between singlet and triplet excited states (ΔE) and thus exhibiting very efficient TADF with microsecond-range lifetimes. In sharp contrast, the corresponding para D-A derivatives, DPApB and CzpB, only display short-lived, normal fluorescence. Organic light-emitting diodes (OLEDs) incorporating the proposed ortho D-A compounds as emitters display orange, greenish-blue, and pure blue emission and exhibit high external quantum efficiency (η). In particular, the pure blue OLEDs based on the proposed ortho D-A emitters with a carbazole donor (CzoB) show a record-high η of 22.6% with CIE color coordinates of (0.139, 0.150), well illustrating the validity of the proposed approach. Upon optical optimization, the η is further improved to 24.1%.

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Section: Resultsmentioning

confidence: 99%

Rigidity-Induced Delayed Fluorescence by Ortho Donor-Appended Triarylboron Compounds: Record-High Efficiency in Pure Blue Fluorescent Organic Light-Emitting Diodes

Lee

Park

et al. 2017

ACS Appl. Mater. Interfaces

140

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“…However, the lifetime of blue phosphorescent OLEDs (PhOLEDs) is too short for use in practical applications. As an alternative to phosphorescent emitters, a thermally activated delayed fluorescent (TADF) emitter has been investigated . Although the lifetime of blue TADF devices is short, TADF OLEDs are candidate high‐efficiency blue OLEDs.…”

Section: Introductionmentioning

confidence: 99%

Recent Progress in High‐Efficiency Blue‐Light‐Emitting Materials for Organic Light‐Emitting Diodes

Byun

Kim

et al. 2017

Adv Funct Materials

516

263

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Organic light-emitting diodes (OLEDs) are increasingly used in displays replacing traditional flat panel displays; e.g., liquid crystal displays. Especially, the paradigm shifts in displays from rigid to flexible types accelerated the market change from liquid crystal displays to OLEDs. However, some critical issues must be resolved for expansion of OLED use, of which blue device performance is one of the most important. Therefore, recent OLED material development has focused on the design, synthesis and application of highefficiency and long-life blue emitters. Well-known blue fluorescent emitters have been modified to improve their efficiency and lifetime, and blue phosphorescent emitters are being investigated to overcome the lifetime issue. Recently, thermally activated delayed fluorescent emitters have received attention due to the potential of high-efficiency and long-living emitters. Therefore, it is timely to review the recent progress and future prospects of high-efficiency blue emitters. In this feature article, we summarize recent developments in blue fluorescent, phosphorescent and thermally activated delayed fluorescent emitters, and suggest key issues for each emitter and future development strategies.

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“…In addition, Adachi et al reported a sky-blue OLED device in the same year and published an article. They studied a sky-blue OLED based on a TADF molecule, 1,2-bis(carbazol-9-yl)-4,5-dicyanobenzene (2CzPN) [ 68 ]. A total of 16 articles were published in 2015.…”

Section: Papersmentioning

confidence: 99%

Status and Challenges of Blue OLEDs: A Review

Siddiqui,

Kumar,

Tsai

et al. 2023

Nanomaterials

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Organic light-emitting diodes (OLEDs) have outperformed conventional display technologies in smartphones, smartwatches, tablets, and televisions while gradually growing to cover a sizable fraction of the solid-state lighting industry. Blue emission is a crucial chromatic component for realizing high-quality red, green, blue, and yellow (RGBY) and RGB white display technologies and solid-state lighting sources. For consumer products with desirable lifetimes and efficiency, deep blue emissions with much higher power efficiency and operation time are necessary prerequisites. This article reviews over 700 papers covering various factors, namely, the crucial role of blue emission for full-color displays and solid-state lighting, the performance status of blue OLEDs, and the systematic development of fluorescent, phosphorescent, and thermally activated delayed fluorescence blue emitters. In addition, various challenges concerning deep blue efficiency, lifetime, and approaches to realizing deeper blue emission and higher efficacy for blue OLED devices are also described.

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High-Efficiency Sky-Blue Organic Light-Emitting Diodes Utilizing Thermally-Activated Delayed Fluorescence

Cited by 8 publications

References 23 publications

Rigidity-Induced Delayed Fluorescence by Ortho Donor-Appended Triarylboron Compounds: Record-High Efficiency in Pure Blue Fluorescent Organic Light-Emitting Diodes

Rigidity-Induced Delayed Fluorescence by Ortho Donor-Appended Triarylboron Compounds: Record-High Efficiency in Pure Blue Fluorescent Organic Light-Emitting Diodes

Recent Progress in High‐Efficiency Blue‐Light‐Emitting Materials for Organic Light‐Emitting Diodes

Status and Challenges of Blue OLEDs: A Review

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