Achieving Pure Green Electroluminescence with CIEy of 0.69 and EQE of 28.2% from an Aza‐Fused Multi‐Resonance Emitter

Zhang, Yuewei; Zhang, Dongdong; Wei, Jinbei; Hong, Xiangchen; Lü, Yang; Da, Hu; Li, Guomeng; Liu, Ziyang; Yang, Chen

doi:10.1002/anie.202008264

Cited by 260 publications

(173 citation statements)

References 58 publications

Supporting

Mentioning

171

Contrasting

Unclassified

Order By: Relevance

“…Based on this strategy, various DABNA analogues exhibiting narrowband TADF emission were reported by our group [5, 6] and others [7–9] . Moreover, introduction of the carbazole unit into the DABNA skeleton facilitated the RISC process [7a] and red‐shifted the emission spectra [7d,f,g] . However, its synthesis involves initial lithiation by alkyllithium to introduce the boron atom, which limits the molecular design and fine tuning of the photophysical properties.…”

Section: Figurementioning

confidence: 99%

Carbazole‐Based DABNA Analogues as Highly Efficient Thermally Activated Delayed Fluorescence Materials for Narrowband Organic Light‐Emitting Diodes

et al. 2020

View full text Add to dashboard Cite

Carbazole‐based DABNA analogues (CzDABNAs) were synthesized from triarylamine by regioselective one‐shot single and double borylation. The reaction proceeded selectively at the ortho position of the carbazolyl group, where the highest occupied molecular orbital is mainly localized owing to the difference in the electron‐donating abilities of the diarylamino and carbazolyl groups. The facile and scalable method enabled synthesis of CzDABNAs, exhibiting narrowband thermally activated delayed fluorescence with emission spectra ranging from deep blue to green. The organic light‐emitting diode devices employing these products as emitters exhibited deep‐blue, sky‐blue, and green emission with high external quantum efficiencies of 19.5, 21.8, and 26.7 %, respectively.

show abstract

Section: Figurementioning

confidence: 99%

Carbazole‐Based DABNA Analogues as Highly Efficient Thermally Activated Delayed Fluorescence Materials for Narrowband Organic Light‐Emitting Diodes

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Moreover, structural modification of the MR structure using aromatic units other than phenyl-based structures to precisely control the MR properties can be a valuable approach to upgrade the TADF properties along with management of boron and nitrogen positions in the MR structure. [126,127] In addition to the material modification methods, a device approach harnessing the singlet excitons of the boron TADF emitters should be adopted. Because the triplet excitons trigger the degradation mechanisms of TADF devices, a triplet exciton managing device structure needs to be employed.…”

Section: Discussionmentioning

confidence: 99%

Three‐ and Four‐Coordinate, Boron‐Based, Thermally Activated Delayed Fluorescent Emitters

Kothavale

Lee

2020

Advanced Optical Materials

136

View full text Add to dashboard Cite

After the first report of organometallic complex-based phosphorescent emitting materials, [5] it was possible to realize 100% internal quantum efficiency in phosphorescent OLEDs (PhOLEDs). [6] Using strong spin-orbit coupling (SOC) of heavy metals such as platinum or iridium, it was possible to surpass the limit of spin statistics and utilize all triplet excitons as well as singlet excitons in PhOLEDs. [7-10] After a huge improvement in the external quantum efficiencies (EQEs) in PhOLEDs, it was possible to commercialize green and red PhOLEDs as replacements for green and red fluorescent OLEDs. However, blue fluorescent OLEDs could not be replaced with PhOLEDs due to lifetime issues. [11,12] Although the currently commercialized OLEDs are mainly based on PhOLEDs, serious issues such as high cost, need for rare materials, and environmental sustainability of the phosphorescent emitters used have forced researchers to identify an alternative to PhOLEDs. [13,14] Recently, TADF OLEDs have emerged as a viable alternative to PhOLEDs due to their capability to exhibit 100% internal quantum efficiency (like PhOLEDs) by harvesting both singlet and triplet excitons through a reverse intersystem crossing (RISC) mechanism. [15-19] As the emitters used in TADF OLEDs are purely organic materials, they are inexpensive, readily available, and offer a large number of design opportunities. They can be easily tuned for different colors and can also serve as efficient host materials in the emitting layers. After the first report of a high EQE TADF OLED in 2012, [20] a number of highly efficient blue, green, and red TADF OLEDs have been reported. [21-36] Although short device lifetime and poor color purity are the main obstacles in commercial application of TADF OLEDs, they are promising because they have obtained high EQEs equal to or higher than that of the PhOLEDs. Commercially applicable, highly efficient, stable, and pure color TADF emitters must have four important characteristics of small singlet-triplet energy gap (ΔE ST), high photoluminescence quantum yield (PLQY), small full width at half-maximum (FWHM), and stability of the emitting materials. However, it is difficult to achieve all four factors in a single molecular design. [17] For example, a small ΔE ST can be obtained through separation of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) using highly twisted molecular structures. However, a high PLQY will be realized by maximizing the overlap between the HOMO and LUMO. The two factors are contradictory, but they are necessary Recent developments in purely organic-material-based thermally activated delayed fluorescence (TADF) emitters are helping to make them suitable for commercial applications in the near future. In spite of their high external quantum efficiencies, the broad emission spectra and short device lifetimes are the main barriers to using TADF emitters. Among the classes of materials, boron-embedded polycyclic aromatic compounds have shown potential as TADF emitte...

show abstract

“…Quite recently, a new class of a fused planar polycyclic aromatic framework with parapositioned electron donating N-atom and electron deficient B-atom have been developed, which induce complementary resonance effects for the offset electron density distributions of HOMO and LUMO orbitals by one atom in an alternating pattern [16][17][18][19][20][21][22][23][24] . This unique MR effect not only features a short-range reorganization of the electron density between excited states and ground states for a small vibrational relaxation of S1, and also minimizes the bonding/antibonding character between adjacent atoms to lower the vibration frequency.…”

Section: And Supplementarymentioning

confidence: 99%

“…MR-TADF emitters with enlarged planar structures have been widely reported, yet only realized blue or sky-blue emission 16,19 . Another strategy may be enhancing CT character for TADF emitters but only limited numbers of green MR-TADF emitters have been developed with this strategy, not to mention red or deep red ones [22][23][24] . Also, the enhanced CT character may break the MR effect and thus broaden emission.…”

Section: And Supplementarymentioning

confidence: 99%

Beating the Limitation of Energy Gap Law Utilizing Deep Red MR-TADF Emitter with Narrow Energy-Bandwidth

Zhang¹,

Zhang²,

Huang³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

The development of high-performance deep red/near-infrared organic light-emitting diodes is hindered by strong non-radiative processes as governed by the energy gap law. Herein, a novel BN-containing skeleton featuring linear N-π-N and B-π-B structure is developed, establishing partial bonding/antibonding character on phenyl core for enhanced electronics coupling of para-positioned B atoms as well as N atoms to narrow energy gaps. Also, the remained MR effect on the peripheral skeleton to maintain the MR effect to minimize the bonding/ antibonding character and suppress vibrational coupling between S0 and S1, thereby fundamentally overcoming the luminescent boundary set by the energy gap law. The target molecules R-BN and R-TBN exhibited extremely high PLQYs of 100% with emission wavelengths at 666 and 686 nm, respectively. The narrow FWMHs of 38 nm observed also testify the effectiveness of vibronic suppression. The corresponding OLEDs afford record-high EQEs over 28% with emission wavelength over 664 nm.

show abstract

Achieving Pure Green Electroluminescence with CIEy of 0.69 and EQE of 28.2% from an Aza‐Fused Multi‐Resonance Emitter

Cited by 260 publications

References 58 publications

Carbazole‐Based DABNA Analogues as Highly Efficient Thermally Activated Delayed Fluorescence Materials for Narrowband Organic Light‐Emitting Diodes

Carbazole‐Based DABNA Analogues as Highly Efficient Thermally Activated Delayed Fluorescence Materials for Narrowband Organic Light‐Emitting Diodes

Three‐ and Four‐Coordinate, Boron‐Based, Thermally Activated Delayed Fluorescent Emitters

Beating the Limitation of Energy Gap Law Utilizing Deep Red MR-TADF Emitter with Narrow Energy-Bandwidth

Contact Info

Product

Resources

About