Ming-Yu Teng

Highly Efficient Green and Blue-Green Phosphorescent OLEDs Based on Iridium Complexes with the Tetraphenylimidodiphosphinate Ligand

Two novel bis-cyclometalated iridium complexes are successfully applied in organic light-emitting diodes (OLEDs). Because of their better carrier transport ability and shorter excited stated lifetimes, good electroluminescence performances of the complexes are observed.

Syntheses, photoluminescence, and electroluminescence of a series of iridium complexes with trifluoromethyl-substituted 2-phenylpyridine as the main ligands and tetraphenylimidodiphosphinate as the ancillary ligand.

Five bis-cyclometalated iridium complexes with tifluoromethyl-substituted 2-phenylpyridine (ppy) at different positions of its phenyl group as the main ligands and tetraphenylimidodiphosphinate (tpip) as the ancillary ligand, 2-6 (1 is a trifluoromethyl-free complex), were prepared, and their X-ray crystallography, photoluminescence, and electrochemistry were investigated. The number and positions of trifluoromethyl groups at the phenyl ring of ppy greatly affected the emission spectra of Ir(3+) complexes, and their corresponding emission peaks at 533, 502, 524, 480, and 542 nm were observed at room temperature, respectively. Constructed with complexes 2-6 as the emitters, respectively, the organic light-emitting diodes (OLEDs) with the structure of indium-tin oxide/1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane (30 nm)/Ir (x wt %):bis[3,5-bis(9H-carbazol-9-yl)phenyl]diphenylsilane (15 nm)/1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (45 nm)/LiF (1 nm)/Al (100 nm) showed good performances. Particularly, device G4 based on 4-trifluoromethyl-substituted complex 4 with x = 8 wt % obtained a maximum luminance of over 39000 cd m(-2) and maximum luminance efficiency (η(L)) and power efficiency (η(p)) of 50.8 cd A(-1) and 29.0 lm W(-1), respectively. The results suggested that all of the complexes 2-6 would have potential applications in OLEDs.

Highly efficient green phosphorescent OLEDs based on a novel iridium complex

A new iridium(III) complex Ir(tfmppy)2(tfmtpip) (1, tfmppy = 4-trifluoromethylphenyl-pyridine, tfmtpip = tetra(4-trifluoromethylphenyl)imidodiphosphinate) was synthesized and applied in organic light-emitting diodes (OLEDs). The devices with the structures of ITO/TAPC (1,1-bis[4-[N,N-di(p-tolyl)amino]phenyl]cyclohexane, 40 nm)/1 (x wt%): mCP (N,N′-dicarbazolyl- 3,5-benzene, 20 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) exhibited a maximum power efficiency (ηp,max) of 113.23 lm W−1 and a maximum current efficiency (ηc,max) of 115.39 cd A−1 (0.01342 mA cm2) at the doping level of 5 wt%, which is among the best performances for Ir(III) complex based OLEDs in the green-light-emitting region. Compared with our former work, the excellent device efficiencies are due to the use of TmPyPB as the electron-transporting/hole-blocking layer which has a relatively higher electron mobility than that of TPBi (2,2′,2′′-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)) and the introduction of the –CF3 moiety to the Ir(III) complex, which can increase the electron mobility of the complex. The device performances proved that the complex has potential applications as an efficient green emitter in OLEDs.

Electron mobility determination of efficient phosphorescent iridium complexes with tetraphenylimidodiphosphinate ligand via transient electroluminescence method

The electron mobility of Alq3 and iridium complexes was determined via transient electroluminescence (EL) method based on ITO (indium tin oxide)/di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane/complex/LiF/Al with short and rectangular driving voltage pulses. Apparent values of the electron mobility (μe) in complexes have been investigated from their onset of EL upon different driving voltages. The result reveals that the μe, 4.31 × 10−6 cm2/V·s, of the efficient phosphorescent material Ir(tfmppy)2(tpip) [1, tfmppy = 4-trifluoromethylphenylpyridine, tpip = tetraphenylimido-diphosphinate] under electric field of 1300 (V/cm)1/2 is as high as that of Alq3, which indicates that the good device performances of 1 are partly due to its high electron mobility.

Color changeable OLEDs controlled by doping ratio and driving voltage with an anthracene derivative doped layer

With 9,10-bis(3,3,3-triphenylprop-1-ynyl)anthracene (BTPYA) doped TPBi as an emissive layer, tunable OLED devices exhibited different emission colors (blue, near-white, green-yellow) controlled by the dopant ratio and driving voltage. The emissions were composed of the electrofluorescence of BTPYA, TPBi, and the electromer of BTPYA, an electroplex formed between BTPYA and TPBi.

Synthesis, chemo-selective properties of substituted 9-aryl-9H-fluorenes from triarylcarbinols and enantiomerical kinetics of chiral 9-methoxy-11-(naphthalen-1-yl)-11H-benzo[a]fluorene

9-Aryl-fluorenes were synthesized conveniently from triarylcarbinols in the presence of TsOH. Notably, the orientation of the intramolecular aromatic substitution reaction was dictated by the nature of the substituents on the aryl rings of triarylcarbinols, owing to electronic and conjugated effects. In particular, triarylcarbinols with (3-methoxy)phenyl and naphthalenyl groups formed benzo[a]fluorenes selectively. Moreover, 9-methoxy-11-(naphthalen-1-yl)-11H-benzo[a] fluorene (2g), with a center of chirality, exists as a mixture of diastereoisomers, due to the restricted rotation of a C–C single bond. First-order rate constants for the enantiomerization of 2g in DMSO were obtained over the temperature from 297 K to 393 K, and thermodynamic parameters were determined as ΔH‡ = 99.7 kJ mol−1, ΔS‡373 K = 37.7 J mol−1 K−1, and ΔG‡373 K = 85.6 kJ mol−1 by Eyring plot analysis.

CCDC 818982: Experimental Crystal Structure Determination

Related Article: Yu-Cheng Zhu, Liang Zhou, Hong-Yan Li, Qiu-Lei Xu, Ming-Yu Teng, You-Xuan Zheng, Jing-Lin Zuo, Hong-Jie Zhang, Xiao-Zeng You|2011|Adv.Mater.|23|4041|doi:10.1002/adma.201101792

1,8-Bis(benz­yloxy)-3,6-diiodo­naphthalene

In the crystal structure of the title compound, C24H18I2O2, one benzene ring is almost coplanar with the naphthyl system [dihedral angle = 6.6 (4)°], whereas the other is almost orthogonal [73.1 (2)°]. The crystal structure is consolidated by C—H⋯O and C—H⋯π interactions.