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Carborane-based host materials were prepared to fabricate deep blue phosphorescence organic light-emitting diodes (PHOLEDs), which constituted three distinctive geometrical structures stemming from the corresponding three different isomeric forms of carboranes, namely, ortho-, meta-, and para-carboranes. These materials consist of two carbazolyl phenyl (CzPh) groups as photoactive units on each side of the carborane carbons to be bis[4-(N-carbazolyl)phenyl]carboranes, o-Cb, m-Cb, and p-Cb. To elaborate on the role of the carboranes, comparative analogous benzene series (o-Bz, m-Bz, and p-Bz) were prepared, and their photophysical properties were compared to show that advantageous photophysical properties were originated from the carborane structures: high triplet energy. Unlike m-Bz and p-Bz, carborane-based m-Cb and p-Cb showed an unconjugated nature between two CzPh units, which is essential for the blue phosphorescent materials. Also, the carborane hosts showed high glass transition temperatures (T(g)) of 132 and 164 °C for m-Cb and p-Cb, respectively. Albeit p-Cb exhibited slightly lower hole mobility when compared to p-Bz, it still lies at the high end hole mobility with a value of 1.1 × 10(-3) cm(2)/(V s) at an electric field of 5 × 10(5) V/cm. Density functional theory (DFT) calculations revealed that triplet wave functions were effectively confined and mostly located at either side of the carbazolyl units for m-Cb and p-Cb. Low-temperature PL spectra indeed provided unequivocal data with higher triplet energy (T(1)) of 3.1 eV for both m-Cb and p-Cb. p-Cb was successfully used as a host in deep blue PHOLEDs to provide a high external quantum efficiency of 15.3% and commission internationale de l'elcairage (CIE) coordinates of (0.15, 0.24).
24Superbly long lifetime over 13,000 h for multiple energy transfer channels in deep blue phosphorescence organic light-emitting diodes with Ir complex under CIEy of 0.17
Superbly long lifetime over 13,000 h for multiple energy transfer channels in deep blue phosphorescence organic light-emitting diodes with Ir complex under CIEy of 0.17
Read more4Decoration of 1,3,5-triazine backbone structure with dibenzofuran and triphenylsilyl blocking groups for high stability n-type host in deep blue phosphorescent organic light-emitting diodes
Decoration of 1,3,5-triazine backbone structure with dibenzofuran and triphenylsilyl blocking groups for high stability n-type host in deep blue phosphorescent organic light-emitting diodes
Read more5Effect of substituted nitrogen atom location on the photophysical and charge transporting properties of carboline derivatives
Effect of substituted nitrogen atom location on the photophysical and charge transporting properties of carboline derivatives
Read more70Bipolar host materials for high efficiency phosphorescent organic light emitting diodes: tuning the HOMO/LUMO levels without reducing the triplet energy in a linear system
Two novel bipolar host materials, BCzSCN and BCzSPO, consisting of an electron deficient cyano or diphenylphosphine oxide acceptor linked to a bicarbazole donor, were designed and synthesized. Their thermal, photophysical and electrochemical properties were systematically investigated. Both BCzSCN and BCzSPO show high triplet energies of over 2.75 eV and could be developed for application in blue phosphorescent organic light-emitting diodes (PHOLEDs), and further for white PHOLEDs. Moreover, the characterization of hole-only and electron-only devices based on BCzSCN and BCzSPO indicate their rather balanced hole/electron injection and transport properties. Blue PHOLEDs containing BCzSCN and BCzSPO as the hosts and FIrpic as a dopant exhibited excellent performance, with maximum external quantum efficiencies of 19.3% and 17.1% respectively. In particular, blue PHOLEDs adopting BCzSCN and BCzSPO exhibited extraordinary low efficiency roll-offs of 5.2% and 7.6% at a brightness of 1000 cd m−2, respectively. Meanwhile, the all-phosphor near-white devices hosted by the two materials were also fabricated, and high external quantum efficiencies of 22.0% and 21.3% were achieved.
Read more6Exciton stabilizing high triplet energy n-type hosts for blue phosphorescent organic light-emitting diodes
Exciton stabilizing high triplet energy n-type hosts for blue phosphorescent organic light-emitting diodes
101Dibenzothiophene derivatives as host materials for high efficiency in deep blue phosphorescent organic light emitting diodes
Various dibenzothiophene derivatives were synthesized as high triplet energy host materials for deep blue phosphorescent organic light-emitting diodes (PHOLEDs) and their device performances were investigated. Dibenzothiophene host materials with a hole transport type carbazole and electron transport type phosphine oxide moieties showed high quantum efficiency and low driving voltage due to balanced charge injection and transport. A high quantum efficiency of 20.2% and only 10% reduction of quantum efficiency at 1000 cd m−2 were demonstrated from the deep blue PHOLEDs with the dibenzothiophene based high triplet energy host materials.
Read more15Synthesis and characterization of blue-emitting Ir(III) complexes with multi-functional ancillary ligands for solution-processed phosphorescent organic light-emitting diodes
Synthesis and characterization of blue-emitting Ir(III) complexes with multi-functional ancillary ligands for solution-processed phosphorescent organic light-emitting diodes
Read more34Bipolar host materials with carbazole and dipyridylamine groups showing high triplet energy for blue phosphorescent organic light emitting diodes
Bipolar host materials with carbazole and dipyridylamine groups showing high triplet energy for blue phosphorescent organic light emitting diodes
Read more34Solution‐Processed Thermally Activated Delayed Fluorescence Exciplex Hosts for Highly Efficient Blue Organic Light‐Emitting Diodes
Two new wide‐bandgap and high‐triplet‐energy acceptor materials, 1,4‐phenylenebis(diphenylphosphine oxide) (2PO) and ((phenylphosphoryl)bis(4,1‐phenylene))bis(diphenylphosphine oxide) (3PO), are designed to construct thermally activated delayed fluorescence (TADF) exciplexes. By mixing them with tris(4‐carbazoyl‐9‐ylphenyl) amine (TCTA), emission from these exciplexes can be easily observed. The forming exciplexes are also studied by delayed transient fluorescence emission to prove their TADF process. Considering the fact that 2PO and 3PO are constructed in a simple interruption process of the phosphine‐oxide group, which has a high triplet energy, the resulting exciplexes can be used to host blue phosphors. Consequently, solution‐processed blue phosphorescent organic light‐emitting diodes (PhOLEDs) based on these compounds demonstrate a current efficiency of 29.2 cd A−1 and 26.8 cd A−1, respectively, which is the first reporting of current efficiencies approaching 30 cd A−1 in blue PhOLEDs with solution‐processed exciplex hosts. Furthermore, relatively low current‐efficiency roll‐off values of 3.5% and 0.4% were observed for 2PO and 3PO‐based devices, respectively, from 100 cd m−2 to 1000 cd m−2.
Read more12Carbazole modified terphenyl based high triplet energy host materials for blue phosphorescent organic light-emitting diodes
Carbazole modified terphenyl based high triplet energy host materials for blue phosphorescent organic light-emitting diodes
Read more25Novel carbazole/pyridine-based host material for solution-processed blue phosphorescent organic light-emitting devices
Novel carbazole/pyridine-based host material for solution-processed blue phosphorescent organic light-emitting devices
11Unveiling the ligand effects on Pt(Ⅱ) carbene complexes for rapid, efficient and narrow-spectra blue phosphorescence
Unveiling the ligand effects on Pt(Ⅱ) carbene complexes for rapid, efficient and narrow-spectra blue phosphorescence
71High efficiency deep blue phosphorescent organic light-emitting diodes
High efficiency deep blue phosphorescent organic light-emitting diodes
4Steric modulation of thermally activated delayed fluorescence-type host for high quantum efficiency in blue phosphorescent organic light-emitting diodes
Steric modulation of thermally activated delayed fluorescence-type host for high quantum efficiency in blue phosphorescent organic light-emitting diodes
Read more48Correlation of the substitution position of diphenylphosphine oxide on phenylcarbazole and device performances of blue phosphorescent organic light-emitting diodes
Two diphenylphosphine oxide modified phenylcarbazole host materials with substituents at 2,7 (PPO27) and 3,6 (PPO36) positions were synthesized and their device performances were correlated with the chemical structure of the host materials. Low driving voltage was obtained in the PPO27host with two diphenylphosphine oxides at 2,7 positions due to reduced band gap. The PPO27 showed better performances in sky blue phosphorescent organic light-emitting diodes, while the PPO36 showed better performances in deep blue phosphorescent organic light-emitting diodes. A high quantum efficiency of 23.9% and power efficiency of 37.5 lm W−1 were achieved in the blue device with PPO27host.
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