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.

Platinum-Functionalized Chiral Molecular Squares as Light-Emitting Materials

2004 ◽  
Vol 846 ◽  
Author(s):  
Lin Zhang ◽  
Yu-Hua Niu ◽  
Alex K.-Y. Jen ◽  
Wenbin Lin
Keyword(s):  
Mass Spectrometry ◽  
Luminous Efficiency ◽  
Quantum Yields ◽  
Bridging Ligands ◽  
Maximum Brightness ◽  
Light Emitting ◽  
Visible Luminescence ◽  
Molecular Squares ◽  
Uv Visible ◽  
C Nmr

ABSTRACTA family of new chiral metallocycles based on Pt(II) diimine metallocornors and bis(acetylene) bridging ligands have been synthesized, and characterized by a variety of techniques including 1H and 13C NMR, UV-visible, luminescence, infrared, and circular dichroism (CD) spectroscopies, and mass spectrometry. All metallocycles exhibit very strong phosphorescence with quantum yields of 8.3 to 15.7%. Chiral Pt(II)-based molecular squares were used as the light-emitting layer in multiplayer devices, and a maximum brightness of 5470 cd/m2 with a maximum luminous efficiency of 0.93 cd/A was achieved.

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).

A New Bis-Cyclometalated Iridium (III) Complex as a Triplet Emitter in Organic Light Emitting Devices

2005 ◽  
Vol 871 ◽  
Author(s):  
Rupasree R Das ◽  
Ohyun Kwon ◽  
Younghun Byun ◽  
Yi-Yeol Lyu ◽  
Myeong Suk Kim ◽  
...  
Keyword(s):  
Density Functional ◽  
Blue Color ◽  
Functional Theory ◽  
Maximum Brightness ◽  
Ancillary Ligands ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Ligand Charge Transfer ◽  
Center Density ◽  
D Orbitals

AbstractWe report a new Iridium(III) complex and the study of its optical, electrochemical and electroluminescence properties. The crystal structure shows an octahedral environment around Ir(III) center. Density functional theory (DFT) calculations indicate the contribution of the d-orbitals of Ir and the π-orbitals of the cyclometalating and ancillary ligands toward HOMO, whereas LUMO is concentrated on only the cyclometalating ligand. These complexes emit in the sky blue color region from an admixture of triplet metal-to-ligand-charge-transfer (3MLCT) and ligand π-π* states. A maximum external (ηex) quantumefficiency and luminance efficiency of 2.4% and 5.5 cd/A at 0.12 mA/cm2 was obtained from the device consisting of a 5% doped polymeric and low molecular host. A maximum brightness of 10,200 cd/m2 at 14.8 V was obtained from the device.

Synthesis and Light-Emtting Diodes Properties of Two New Fluorene Based Copolymers

2011 ◽  
Vol 295-297 ◽  
pp. 274-277 ◽  
Author(s):  
Jian Hua Huang ◽  
Xiang Hui Ye ◽  
Chuan Lang Zhan ◽  
Gui Yu ◽  
Yun Qi Liu ◽  
...  
Keyword(s):  
Current Efficiency ◽  
Light Emitting Diodes ◽  
Coupling Reaction ◽  
Suzuki Coupling ◽  
Maximum Brightness ◽  
Suzuki Coupling Reaction ◽  
Light Emitting ◽  
Maximum Current ◽  
Conjugated Copolymers

Two new conjugated copolymers, PFPh and PFTDP, comprised of alternating 9,9-dioctylfluorene and phthalimide (Ph) or thieno [3, 4-c] pyrrole-4,6-dione (TPD) have been synthesized via Suzuki coupling reaction. Polymeric light-emitting diodes (PLED) were fabricated with an ITO/PEDOT: PSS/PVK/Polymer/BCP/Alq/Ca:Ag configuration. The maximum brightness and maximum current efficiency of PLED are 2600cd/m2and 2.52 cd/A for PFPh, and 2300cd/m2and 1.13 cd/A for PFTDP, respectively, which are significantly improved compared with the reported alternating fluorene-unsubstituted phenylene/thiophene systems.

scholarly journals High Stability White Organic Light-Emitting Diode (WOLED) Using Nano-Double-Ultra Thin Carrier Trapping Materials

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Kan-Lin Chen
Keyword(s):  
Indium Tin Oxide ◽  
Molybdenum Trioxide ◽  
Light Emitting Diode ◽  
Charge Trapping ◽  
Color Stability ◽  
Slight Variation ◽  
Maximum Brightness ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light

The structure of indium tin oxide (ITO) (100 nm)/molybdenum trioxide (MoO3) (15 nm)/N,N0-bis-(1-naphthyl)-N,N0-biphenyl-1,10-biphenyl-4,40-diamine (NPB) (40 nm)/4,4′-Bis(2,2-diphenylvinyl)-1,1′-biphenyl (DPVBi) (10 nm)/5,6,11,12-tetraphenylnaphthacene (Rubrene) (0.2 nm)/DPVBi (24 nm)/Rubrene (0.2 nm)/DPVBi (6 nm)/4,7-diphenyl-1,10-phenanthroline (BPhen): cesium carbonate (Cs2Co3) (10 nm)/Al (120 nm) with high color purity and stability white organic light-emitting diode (WOLED) was fabricated. The function of the multiple-ultra-thin material (MUTM), such as Rubrene, is as the yellow light-emitting layer and trapping layer. The results show that the MUTM has an excellent carrier capture effect, resulting in high color stability of the device at different applied voltages. The Commissions Internationale De L’Eclairage (CIE) coordinate of this device at 3~7 V is few displacement and shows a very slight variation of (±0.01, ±0.01). The maximum brightness of 9986 cd/m2and CIE coordinates of (0.346, 0.339) are obtained at 7 V. The enhanced performance of the device may result from the direct charge trapping in MUTM and it can be found in the electroluminescence (EL) process.

Injecting Inter-Layers and the Built-in Potential of Blue Polymer Light-Emitting Diodes

2000 ◽  
Vol 660 ◽  
Author(s):  
Thomas M. Brown ◽  
Ian S. Millard ◽  
David J. Lacey ◽  
Jeremy H. Burroughes ◽  
Richard H. Friend ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Basic Structure ◽  
Thin Layers ◽  
Carrier Injection ◽  
Semiconducting Polymer ◽  
Light Emitting ◽  
Physical Mechanisms ◽  
Organic Solid ◽  
Polymer Light Emitting Diodes

ABSTRACTThe semiconducting-polymer/injecting-electrode heterojunction plays a crucial part in the operation of organic solid state devices. In polymer light-emitting diodes (LEDs), a common fundamental structure employed is Indium-Tin-Oxide/Polymer/Al. However, in order to fabricate efficient devices, alterations to this basic structure have to be carried out. The insertion of thin layers, between the electrodes and the emitting polymer, has been shown to greatly enhance LED performance, although the physical mechanisms underlying this effect remain unclear. Here, we use electro-absorption measurements of the built-in potential to monitor shifts in the barrier height at the electrode/polymer interface. We demonstrate that the main advantage brought about by inter-layers, such as poly(ethylenedioxythiophene)/poly(styrene sulphonic acid) (PEDOT:PSS) at the anode and Ca, LiF and CsF at the cathode, is a marked reduction of the barrier to carrier injection. The electro- absorption results also correlate with the electroluminescent characteristics of the LEDs.

Controlled Injection of Holes into ALQ3 Based Oleds by Means of An Oxidized Transport Layer

2001 ◽  
Vol 708 ◽  
Author(s):  
Mathew K. Mathai ◽  
Keith A. Higginson ◽  
Bing R. Hsieh ◽  
Fotios Papadimitrakopoulos
Keyword(s):  
Indium Tin Oxide ◽  
Oxidative Degradation ◽  
Transport Layer ◽  
Hole Injection ◽  
Carrier Injection ◽  
Salt Loading ◽  
Light Emitting ◽  
Hole Transporting ◽  
Intrinsic Degradation ◽  
Variable Conductivity

ABSTRACTIn this paper we report a method for tuning the extent of hole injection into the active light emitting tris- (8-hydroxyquinoline) aluminum (Alq3) layer in organic light emitting diodes (OLEDs). This is made possible by modifying the indium tin oxide (ITO) anode with an oxidized transport layer (OTL) comprising a hole transporting polycarbonate of N,N'-bis(3-hydroxymethyl)-N,N'-bis(phenyl) benzidine and diethylene glycol (PC-TPB-DEG) doped with varying concentrations of antimonium hexafluoride salt of N,N,N',N'-tetra-p-tolyl-4,4'-biphenyldiamine (TMTPD+ SbF6-). The conductivity of the OTL can be changed over three orders of magnitude depending on salt loading. The analysis of hole and electron current variations in these devices indicates that optimizing the conductivity of the OTL enables the modulation of hole injection into the Alq3 layer. The bipolar charge transport properties for OLEDs in which the interfacial carrier injection barriers have been minimized, are governed by the conductivities of the respective layers and in this case it is shown that the variable conductivity of the OTL does allow for better control of the same. Accordingly, varying the concentration of holes in the device indicates that beyond an optimum concentration of holes, further hole injection results in the formation of light quenching cationic species and the initiation of oxidative degradation processes in the Alq3 layer, thus accelerating the intrinsic degradation of these devices. The variable conductivity of the OTL can hence be used to minimize the occurrence of these processes.

scholarly journals High-performance quasi-2D perovskite light-emitting diodes: from materials to devices

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Li Zhang ◽  
Changjiu Sun ◽  
Tingwei He ◽  
Yuanzhi Jiang ◽  
Junli Wei ◽  
...  
Keyword(s):  
Energy Transfer ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Structural Characteristics ◽  
Quantum Yields ◽  
Research Directions ◽  
Light Emitting ◽  
Perovskite Materials ◽  
Quantum Confinement Effects ◽  
Semiconducting Properties

AbstractQuasi-two-dimensional (quasi-2D) perovskites have attracted extraordinary attention due to their superior semiconducting properties and have emerged as one of the most promising materials for next-generation light-emitting diodes (LEDs). The outstanding optical properties originate from their structural characteristics. In particular, the inherent quantum-well structure endows them with a large exciton binding energy due to the strong dielectric- and quantum-confinement effects; the corresponding energy transfer among different n-value species thus results in high photoluminescence quantum yields (PLQYs), particularly at low excitation intensities. The review herein presents an overview of the inherent properties of quasi-2D perovskite materials, the corresponding energy transfer and spectral tunability methodologies for thin films, as well as their application in high-performance LEDs. We then summarize the challenges and potential research directions towards developing high-performance and stable quasi-2D PeLEDs. The review thus provides a systematic and timely summary for the community to deepen the understanding of quasi-2D perovskite materials and resulting LED devices.

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