A Solution‐Processed Resonance Host for Highly Efficient Electrophosphorescent Devices with Extremely Low Efficiency Roll‐off

Tao, Ye; Guo, Xin; Hao, Lin; Chen, Runfeng; Li, Huanhuan; Chen, Yuehua; Zhang, Xinwen; Lai, Wen‐Yong; Huang, Wei

doi:10.1002/adma.201503108

Cited by 71 publications

(48 citation statements)

References 35 publications

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“…Impressively, much improved device performance with CE of 36.8 cd A −1 , PE of 25.5 lm W −1 , and EQE of 19.4% were achieved (Figure b). More importantly, very low efficiency roll‐off of CE and EQE were observed, which are only 1.1% and 1.4% at 1000 cd m −2 ; these values are among the best of the recently reported blue PhOLEDs …”

Section: Methodssupporting

confidence: 56%

High‐Performance All‐Aryl Phenazasilines via Metal‐Free Radical‐Mediated CH Silylation for Organic Light‐Emitting Diodes

Shen

Chen

et al. 2018

Advanced Optical Materials

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complicated synthetic routes to prepare heteroatom-containing materials with specifically introduced heteroatoms on the desired positions of an aromatic molecule, and it becomes even more challenging, when multiple and/or multitype heteroatoms are designed to be introduced. [5][6][7] Phenazasilines, which contain both Si and N heteroatoms in a fused six-membered ring, are typical examples. [8,9] Structurally similar to the popular donor moiety of 9,10-dihydroacridine by replacing its 9-C with Si, [10] phenazasilines can benefit from both 9,10-dihydroacridine-alike architecture and Si incorporation, exhibiting intrinsically promising properties as hole-transporting materials for organic field effect transistors [11] with a hole mobility of 10 −4 cm 2 V −1 s −1 and an ON-OFF ratio close to 10 5 , thermally activated delayed fluorescence (TADF) emitters [12] for organic light emitting diodes (OLEDs) with external quantum efficiency (EQE) up to 22.3%, and host materials [13] for phosphorescent OLEDs (PhOLEDs) with EQE of 12%. Nevertheless, the synthesis of phenazasilines, either traditionally through extended heating of diphenylsilane with phenothiazines [14] and cyclization reaction between 2,2′-dilithiodiarylamine intermediates and dichlorosilanes, [15] or recently by rhodium-catalyzed double activation of SiH and CH bonds for dehydrogenation and SiC coupling, [13] suffers from the low yields, complicated precursors, long synthetic routes, or high chemical costs. These synthetic difficulties significantly hinder the investigations and applications of phenazasilines, although they have already shown promising optical and electronic properties for high-performance device applications due to the combined effects of Si and N heteroatom incorporation.With planar π-conjugated molecular structure, phenazasilines are especially attractive for OLEDs to function as emitters, charge transporters, and host materials. However, due to the planar molecular geometry of phenazasilines with a phenyl-fused azasiline ring, strong π-π stacking and heavy intermolecular interaction are generally observed, especially in the solid state, leading to broad and redshifted excimer emission and coarse film morphology. [16,17] To alleviate the intermolecular interactions, bulky phenyl substituents on the Heteroatom-containing organic molecules show a unique combination of properties for high-performance optoelectronic applications. With both Si and N heteroatoms in an aromatic architecture, phenazasilines are promising for optoelectronic devices, except for their synthetic difficulties. Through a newly developed two-step SiH/CH coupling silylation in a metal-free intramolecular radical-mediated catalysis mechanism, all-aryl phenazasilines that can be hardly synthesized by previous methods are facilely prepared and found to have excellent optoelectronic properties with both high thermal stability and high solubility due to the effects of bulky diphenyl substituents on Si, which cannot only strengthen the intramolecular interactions but also ...

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Section: Methodssupporting

confidence: 56%

High‐Performance All‐Aryl Phenazasilines via Metal‐Free Radical‐Mediated CH Silylation for Organic Light‐Emitting Diodes

Shen

Chen

et al. 2018

Advanced Optical Materials

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“…Complementary‐color white‐emitting PhOLEDs (device WA–WD ) were fabricated with the configuration of ITO/PEDOT: PSS (80 nm)/EML (35 nm)/TmPyPB (60 nm)/Liq (1 nm)/Al (Figure S15, Supporting Information) 11. The EMLs of WA–WD consist of TNPhB ( WA ), DNPhCzB ( WB ), NPhDCzB ( WC ), or TCzB ( WD ): 20 wt% TAPC as the host and FIrpic (15 wt%), bis(2‐phenylbenzothiazole) (acetylacetonate)‐iridium(III) (Ir(bt) 2 acac) (1 wt%) as the blue and orange‐red emitter, respectively 35.…”

Section: Resultsmentioning

confidence: 99%

Star‐Shaped Boron‐Containing Asymmetric Host Materials for Solution‐Processable Phosphorescent Organic Light‐Emitting Diodes

Jin

Tao

et al. 2018

Advanced Science

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Boron‐containing compounds have attracted considerable attention because of their electron‐accepting properties, and they are widely used in a variety of fields. However, due to the essential requirement to protect the empty pz‐orbital of the boron atom using large steric hindrance or rigid groups, borane derivatives generally show poor solubility and are rarely reported as acceptor units to construct bipolar host materials for phosphorescent organic light‐emitting diodes (PhOLEDs). Here, a combined star‐shaped and asymmetric donor–acceptor molecular design strategy to improve the solubility and fine tune the optical and electronic properties of boron‐containing materials is presented. High thermal stability, solvent solubility, solution processability, and triplet energy are achieved simultaneously. With the thus‐designed boron‐containing bipolar molecules as host materials, the solution‐processed PhOLEDs exhibit high device performances, which are comparable to the vacuum‐processed counterparts, showing high external quantum efficiencies up to 18.5% and 14.5% in blue and white PhOLEDs, respectively. These results demonstrate the great potential of the star‐shaped and symmetry‐breaking borane derivatives in solution‐processable organic optoelectronic devices.

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“…Commonly, the host‐dopant systems are generally adopted to controllably eliminate the triplet‐involved quench effects of emissive phosphors in the PhOLEDs . The basic metrics of solution‐processed hosts are excellent electrical property for endowing efficient and balanced carrier injection and flux, and high triplet energy ( E T ) levels for maintaining exothermic energy migration from the hosts to dopants and confining the triplet excitons in EML . Furthermore, additional requirements of hosts have to be simultaneously fulfilled to support high‐efficiency solution‐processed PhOLEDs: i) good solubility in common organic solvent to fabricate stable, uniform and pin‐hole free films, ii) high thermal and chemical stability to endow high temperature thermal annealing for eliminating organic solvents and, iii) excellent compatibility with the dopants to reduce the phase separation and elongate the device operation lifetime.…”

Section: Device Performances Of Dczsi and Dsidczsi Hosted Blue Pholedsmentioning

confidence: 99%

Multiple σ–π Conjugated Molecules with Selectively Enhanced Electrical Performance for Efficient Solution‐Processed Blue Electrophosphorescence

Zhi

et al. 2019

Advanced Optical Materials

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Phosphorescent organic light-emitting diodes (PhOLEDs) have attracted intense attention owing to their theoretical 100% internal quantum efficiency through simultaneously utilizing singlet and triplet excitons. [1] With the tremendous efforts over the past few decades, the thermalevaporated electrophosphorescence devices with excellent external quantum efficiencies (EQEs) and operation lifetimes have been achieved. [2][3][4][5][6] Nevertheless, the development of high-efficiencies blue PhOLEDs remains as a daunting and forbidden challenge although blue emission is indispensable to improve color rendering index and color gamuts. [7][8][9][10][11][12] Moreover, the vacuum-deposited PhOLEDs require complicated technological processes and precisely controlling of concentrations of different materials in emission layer (EML) for realizing high device performance, which leads to relatively high fabrication costs. Solution-processed PhOLEDs based on spin-coating, blade coating and/or inkjet printing have been introduced with insistence because of their ultimate potential in facilitating largearea, low-cost, and high-efficiency flat-panel display as well as lighting products. [13,14] However, it is still quite difficult to develop solution-processed organic semiconductors simultaneously with the characteristics of good-solubility, large bandgap, and good carrier transportation for high-performance solutionprocessed blue PhOLEDs, which are fundamentally important for next-generation lighting sources and displays technologies.Commonly, the host-dopant systems are generally adopted to controllably eliminate the triplet-involved quench effects of emissive phosphors in the PhOLEDs. [15] The basic metrics of solution-processed hosts are excellent electrical property for endowing efficient and balanced carrier injection and flux, and high triplet energy (E T ) levels for maintaining exothermic energy migration from the hosts to dopants and confining the triplet excitons in EML. [16,17] Furthermore, additional requirements of hosts have to be simultaneously fulfilled to support high-efficiency solution-processed PhOLEDs: [18,19] i) good solubility in common organic solvent to fabricate stable, uniform and pin-hole free films, ii) high thermal and chemical stability to endow high temperature thermal annealing for eliminating Selectively and controllably regulating molecular functions of organic optoelectronic materials with high solubility for solution-processible devices is highly desired but remains as one of the most significant challenges in material science. Here, a concise molecular design strategy is reported to achieve effective electronic communications using efficient d-orbital participated σ-π conjugations between Si and π unit for purposely modulating the electrical properties of organic optoelectronic materials. Through a two-step reaction in high yield, DSiDCzSi with the enhanced σ-π conjugation is facilely constructed by introducing multiple triphenylsilanes into carbazole unit. Impressively, DSiD-CzSi demonstrates...

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A Solution‐Processed Resonance Host for Highly Efficient Electrophosphorescent Devices with Extremely Low Efficiency Roll‐off

Cited by 71 publications

References 35 publications

High‐Performance All‐Aryl Phenazasilines via Metal‐Free Radical‐Mediated CH Silylation for Organic Light‐Emitting Diodes

High‐Performance All‐Aryl Phenazasilines via Metal‐Free Radical‐Mediated CH Silylation for Organic Light‐Emitting Diodes

Star‐Shaped Boron‐Containing Asymmetric Host Materials for Solution‐Processable Phosphorescent Organic Light‐Emitting Diodes

Multiple σ–π Conjugated Molecules with Selectively Enhanced Electrical Performance for Efficient Solution‐Processed Blue Electrophosphorescence

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