Manipulating the positions of CH⋯N in acceptors of pyrimidine–pyridine hybrids for highly efficient sky-blue thermally activated delayed fluorescent OLEDs

Zhang, Qing; Sun, Shuaiqiang; Lv, Xialei; Liu, Wei; Zeng, Hongxia; Guo, Runda; Ye, Shaofeng; Leng, Panpan; Xiang, Songpo; Wang, Lei

doi:10.1039/c8qm00382c

Cited by 29 publications

(16 citation statements)

References 52 publications

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“…Organic materials with extended π-conjugation along their backbone have been intensively studied because of their applications in a wide range of electronic and optoelectronic devices . Among π-conjugated systems, push–pull molecules (D–A), constituted of a conjugated π-electron system asymmetrically substituted by an electron-donor group (D) and an electron-withdrawing one (A), as well as molecules with donor–acceptor–donor (D–A–D) architecture have been widely investigated to construct organic low-band gap materials for optoelectronic devices, such as organic light-emitting diodes (OLEDs), organic photovoltaic cells (OPVs) and organic solar cells, organic field-effect transistors, nonlinear optics (NLO), and fluorescent chemosensors …”

Section: Introductionmentioning

confidence: 99%

Synthesis of D–A–A and D–A–D Pyrimidine π-Systems Using Triorganoindium Reagents: Optical, Vibrational, and Electrochemical Studies

et al. 2019

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A series of donor−acceptor−acceptor (D−A− A) and donor−acceptor−donor (D−A−D) systems based on a pyrimidine π-spacer with various substituents at the C-2 position has been successfully prepared. The synthesis involved site-selective palladium cross-coupling reactions of chloropyrimidines with triorganoindium reagents and proceed in good yields and with atom economy. 4-(N,N-Diphenylamino)phenyl was chosen as the donor group and thien-2-yl dicyanovinylene as the acceptor one. The optical, vibrational, electrochemical, and density functional theory (DFT) calculations of these molecular systems were analyzed, and experimental values show the important role of the substituents at the C-2 position of the pyrimidine with stronger electron accepting ability, absorption in a wide range of UV/vis, acceptable fluorescence lifetime, and effective intramolecular charge transfer (ICT) properties. The ICT was observed in both series by the bathochromic shift on increasing the polarity of the solvent. In addition, DFT calculations found lower lowest unoccupied molecular orbitals of D−A−A molecules that suggest good electron ejection and transportation, being good properties for their application in various organic optoelectronic devices.

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Section: Introductionmentioning

confidence: 99%

Synthesis of D–A–A and D–A–D Pyrimidine π-Systems Using Triorganoindium Reagents: Optical, Vibrational, and Electrochemical Studies

et al. 2019

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“…Furthermore, the intramolecular hydrogen bonding between the nitrogen in pyridine ring of phenyl(pyridyl)methanone and the adjacent C–H bonds of the carbazole group with a distance of 2.52 Å in 3CPyM-PXZ was observed. The existence of intramolecular hydrogen bonding was expected to restrict the intramolecular rotation, which will increase the PLQY in the solid state and increase the molecular stability. ,− Moreover, the similar intramolecular hydrogen bonding was not found in the single crystals of CBM-DMAC and CBM-PXZ. For other compounds, even though the crystal structures were not obtained, the existence of similar hydrogen bonding from the DFT optimization could be predicted.…”

Section: Resultsmentioning

confidence: 99%

Molecular Engineering of Thermally Activated Delayed Fluorescence Emitters with Aggregation-Induced Emission via Introducing Intramolecular Hydrogen-Bonding Interactions for Efficient Solution-Processed Nondoped OLEDs

Zhao

Zheng

et al. 2019

ACS Appl. Mater. Interfaces

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Purely organic luminescent materials concurrently exhibiting thermally activated delayed fluorescence (TADF) and aggregation-induced emission (AIE) features are in great demand due to their high efficiency in aggregationstate toward efficient nondoped OLEDs. Herein, a class of TADF emitters adopting phenyl(pyridyl)methanone as electron-accepting segments and di(tert-butyl)carbazole and 9,9-dimethyl-9,10-dihydroacridine (or phenoxazine) as electron-donating groups are designed and synthesized. The existence of intramolecular hydrogen bonding is conducive to minish the energy difference between a singlet and a triplet (ΔE st ), suppress nonradiative decay, and increase the luminescence efficiency. By using 3CPyM-DMAC as the emitter, the nondoped device via a solution process realize a high current efficiency (CE) and external quantum efficiency (EQE) of 35.4 cd A −1 and 11.4%, respectively, which is superior to that of CBM-DMAC with a CE and EQE of 14.3 cd A −1 and 6.7%. This work demonstrates a promising tactic to the establishment of TADF emitters with AIE features via introducing intramolecular hydrogen bonding.

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“…The melting point ( T m ) of PyDCz and PymDCz is as high as 229 and 258 °C (Table ), respectively. These results indicate that the thermal properties are enhanced by the introduction of additional nonbonding CH···N interactions, suggesting their promising potential in the thermally evaporated device fabrications …”

Section: Results and Discussionmentioning

confidence: 99%

“…Here, we introduce NCIs into the host materials of blue PhOLEDs in D-A-D molecular architectures to explore the effect of the NCIs on the electrical performance of organic semiconductors. Carbazole with sufficiently high triplet energy and good hole-transporting ability was selected as the donor unit, and the strong electron-deficient nitrogen six-membered heterocyclic rings of pyridine, pyrimidine, and pyrazine were used as the accepters to construct three new D-A-D host molecules with noncovalent intramolecular CH···N interactions. ,− These host molecules with high E T were facilely prepared through a one-step C–N coupling reaction in high yields . Combined computational and experimental investigations showed that the intramolecular CH···N interactions can successfully tune the molecular conformation and modulate their corresponding packing modes in solid states.…”

Section: Introductionmentioning

confidence: 99%

Tuning Intramolecular Conformation and Packing Mode of Host Materials through Noncovalent Interactions for High-Efficiency Blue Electrophosphorescence

Chen

Tao

et al. 2019

ACS Omega

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Molecular conformation plays an important role in tuning the packing modes of organic optoelectronic materials to achieve enhanced and/or balanced charge transport. Here, we introduce the noncovalent intramolecular interactions to the host materials of phosphorescent organic light-emitting diodes (PhOLEDs). Different numbers and/or positions of intramolecular CH···N noncovalent interactions were constructed by using different N-heterocycles of pyridine, pyrimidine, and pyrazine as acceptor units and carbazole as the donor unit in a donor-acceptor-donor (D-A-D) motif. Thus, designed D-A-D molecules were synthesized facilely through a one-step Ullmann reaction in high yields, showing varied intramolecular interactions to regulate the molecular conformation significantly. Impressively, owing to the quasi-parallel molecular conformation, which is beneficial for forming facile transporting channels of both holes and electrons, the newly designed host material of 9,9′-(pyridine-2,5-diyl)bis(9 H -carbazole) exhibits good device performance of blue PhOLEDs with current, power, and external quantum efficiencies up to 33.0 cd A –1 , 32.1 lm W –1 , and 16.3%, respectively. This work highlights the significant importance of the noncovalent interactions in designing advanced organic semiconductors for high-performance optoelectronic devices.

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Manipulating the positions of CH⋯N in acceptors of pyrimidine–pyridine hybrids for highly efficient sky-blue thermally activated delayed fluorescent OLEDs

Abstract: Manipulating the positions of CH⋯N in acceptors along the orientation of the electron cloud distributions.

Cited by 29 publications

References 52 publications

Synthesis of D–A–A and D–A–D Pyrimidine π-Systems Using Triorganoindium Reagents: Optical, Vibrational, and Electrochemical Studies

Synthesis of D–A–A and D–A–D Pyrimidine π-Systems Using Triorganoindium Reagents: Optical, Vibrational, and Electrochemical Studies

Molecular Engineering of Thermally Activated Delayed Fluorescence Emitters with Aggregation-Induced Emission via Introducing Intramolecular Hydrogen-Bonding Interactions for Efficient Solution-Processed Nondoped OLEDs

Tuning Intramolecular Conformation and Packing Mode of Host Materials through Noncovalent Interactions for High-Efficiency Blue Electrophosphorescence

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