scholarly journals Enhanced quantum yields by sterically demanding aryl-substituted β-diketonate ancillary ligands

2018 ◽  
Vol 14 ◽  
pp. 664-671 ◽  
Author(s):  
Rebecca Pittkowski ◽  
Thomas Strassner
Keyword(s):  
Quantum Yields ◽  
Ancillary Ligands ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Emission Color ◽  
Decay Times ◽  
Sterically Demanding ◽  
Cyclometalated Complexes ◽  
Blue Spectral Region ◽  
Methyl Phenyl

Luminescent organometallic platinum(II) compounds are of interest as phosphors for organic light emitting devices. Their emissive properties can be tuned by variation of the ligands or by specific electron-withdrawing or electron-donating substituents. Different ancillary ligands can have a profound impact on the emission color and emission efficiency of these complexes. We studied the influence of sterically hindered, aryl-substituted β-diketonates on the emission properties of C^C* cyclometalated complexes, employing the unsubstituted methyl-phenyl-imidazolium ligand. The quantum yield was significantly enhanced by changing the auxiliary ligand from acetylacetonate, where the corresponding platinum(II) complex shows only a very weak emission, to mesityl (mes) or duryl (dur) substituted acetylacetonates. The new complexes show very efficient emission with quantum yields >70% in the sky-blue spectral region (480 nm) and short decay times (<3 μs).

scholarly journals Simple Synthesis of Red Iridium(III) Complexes with Sulfur-Contained Four-Membered Ancillary Ligands for OLEDs

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2599
Author(s):  
Meng-Xi Mao ◽  
Fang-Ling Li ◽  
Yan Shen ◽  
Qi-Ming Liu ◽  
Shuai Xing ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Quantum Yields ◽  
Rapid Preparation ◽  
Maximum Brightness ◽  
Ancillary Ligands ◽  
Light Emitting ◽  
Maximum Current ◽  
Electron Donating Groups ◽  
Sulfur Containing ◽  
Main Ligand

Phosphorescent iridium(III) complexes have been widely researched for the fabrication of efficient organic light-emitting diodes (OLEDs). In this work, three red Ir(III) complexes named Ir-1, Ir-2, and Ir-3, with Ir-S-C-S four-membered framework rings, were synthesized efficiently at room temperature within 5 min using sulfur-containing ancillary ligands with electron-donating groups of 9,10-dihydro-9,9-dimethylacridine, phenoxazine, and phenothiazine, respectively. Due to the same main ligand of 4-(4-(trifluoromethyl)phenyl)quinazoline, all Ir(III) complexes showed similar photoluminescence emissions at 622, 619, and 622 nm with phosphorescence quantum yields of 35.4%, 50.4%, and 52.8%, respectively. OLEDs employing these complexes as emitters with the structure of ITO (indium tin oxide)/HAT-CN (dipyra-zino[2,3-f,2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile, 5 nm)/TAPC (4,4′-cyclohexylidenebis[N,N-bis-(4-methylphenyl)aniline], 40 nm)/TCTA (4,4″,4″-tris(carbazol-9-yl)triphenylamine, 10 nm)/Ir(III) complex (10 wt%): 2,6DCzPPy (2,6-bis-(3-(carbazol-9-yl)phenyl)pyridine, 10 nm)/TmPyPB (1,3,5-tri(mpyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) achieved good performance. In particular, the device based on complex Ir-3 with the phenothiazine unit showed the best performance with a maximum brightness of 22,480 cd m−2, a maximum current efficiency of 23.71 cd A−1, and a maximum external quantum efficiency of 18.1%. The research results suggest the Ir(III) complexes with a four-membered ring Ir-S-C-S backbone provide ideas for the rapid preparation of Ir(III) complexes for OLEDs.

scholarly journals Bright Alloy CdZnSe/ZnSe QDs with Nonquenching Photoluminescence at High Temperature and Their Application to Light-Emitting Diodes

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Tingting Zhang ◽  
Xugu Zhang ◽  
Peizhi Yang ◽  
Jinke Bai ◽  
Chun Chang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Quantum Yields ◽  
Excellent Performance ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Maximum Current Density ◽  
Luminescence Efficiency ◽  
Maximum Current ◽  
Pl Quenching

Stable luminance properties are essential for light-emitting devices with excellent performance. Thermal photoluminescence (PL) quenching of quantum dots (QDs) under a high temperature resulting from a surface hole or electron traps will lead to unstable and dim brightness. After treating CdZnSe/ZnSe QDs with TBP, which is a well-known passivation reagent of the anions, the excess Se sites on the surface of the QDs were removed and their PL quantum yields (QYs) was improved remarkable. Furthermore, after TBP treatment, the CdZnSe/ZnSe QDs exhibit no quenching phenomena even at a high temperature of 310°C. The electroluminescent light-mitting diodes based on the QDs with TBP treatment also demonstrated satisfied performance with a maximum current density of 1679.6 mA/cm2, a peak luminance of 89500 cd/m2, and the maximum values of EQE and luminescence efficiency are 15% and 14.9 cd/A, respectively. The performance of the fabricated devices can be further improved providing much more in-depth studies on the CdZnSe/ZnSe QDs.

Thickness dependent emission color of organic white light-emitting devices

2003 ◽  
Vol 137 (1-3) ◽  
pp. 1101-1102 ◽  
Author(s):  
Jing Feng ◽  
Yu Liu ◽  
Feng Li ◽  
Yue Wang ◽  
Shiyong Liu
Keyword(s):  
White Light ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Emission Color

scholarly journals Спектроскопические свойства полимерных пленок, активированных супрамолекулярным наноалмазным комплексом европия с батофенантролином

2019 ◽  
Vol 127 (8) ◽  
pp. 236
Author(s):  
В.А. Лапина ◽  
Т.А. Павич ◽  
П.П. Першукевич
Keyword(s):  
Emission Band ◽  
High Efficiency ◽  
Matrix Material ◽  
Quantum Yields ◽  
Excitation Spectra ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Luminescent Films ◽  
Laser Media ◽  
Main Emission Band

For the first time, using the supramolecular diamond-containing europium (III) complex with bathophenanthroline, new luminescent films were obtained, converting UV radiation in the wavelength range of 220–410 nm with high efficiency to luminescence of europium ions, with the ability to control the degree of monochromaticity of radiation in the main emission band of Eu3+ ions with maximum of 615 nm. It was found that the shape of the excitation spectra, the half-width of the main emission band of 615 nm (transition 5D0–7F2), the values of quantum yields (within ~ 0.3–0.8) depend on the type of matrix material. The proposed optical materials can be used in the development of various light-emitting devices: screens, indicators, solar concentrators, organic light-emitting diodes, laser media.

Interlayer Interactions in Self-Assembled Poly(Phenylene Vinylene) Multilayer Heterostructures, Implications for Light-Emitting and Photorectifying Diodes

1994 ◽  
Vol 369 ◽  
Author(s):  
A.C. Fou ◽  
O. Onitsuka ◽  
M. Ferreira ◽  
M.F. Rubner ◽  
B.R. Hsieh
Keyword(s):  
Ultrathin Films ◽  
Self Assembly ◽  
Organic Light Emitting Diodes ◽  
Phenylene Vinylene ◽  
Layer By Layer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Emission Color ◽  
Multilayer Heterostructures ◽  
Self Assembled

AbstractLayer-by-layer molecular self-assembly has been used to fabricate multilayer heterostructures containing poly(phenylene vinylene) (PPV) and a variety of polyanions. These ultrathin films exhibit widely different photoluminescence intensities and peak positions (emission color) depending on the polyanion used. The characteristics of light-emitting devices based on such films are described. This represents the first demonstration of working organic light-emitting diodes, the active layer of which consists of ultrathin, self-assembled films of between 130 - 500 Å

Sign in / Sign up

Export Citation Format

Share Document