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.

High-Temperature Synthesis of CdSe-Based Core/Shell, Core/Shell/Shell, and Core/Graded-Shell Nanoplatelets for Stable and Efficient Narrowband Emitters

2019 ◽  
Author(s):  
Aurelio A. Rossinelli ◽  
Henar Rojo ◽  
Aniket S. Mule ◽  
Marianne Aellen ◽  
Ario Cocina ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Equilibrium Shape ◽  
Size Variation ◽  
Crystal Defects ◽  
Atomic Scale ◽  
Quantum Yields ◽  
Core Shell ◽  
Compositional Gradient ◽  
High Quality

<div>Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, which are well known to improve the performance of quantum dots. <br></div><div>Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.</div>

scholarly journals Strategies to Improve Luminescence Efficiency and Stability of Blue Perovskite Light‐Emitting Devices

Small Science ◽  
2021 ◽  
pp. 2000048
Author(s):  
Xiao-Yan Qian ◽  
Ying-Yi Tang ◽  
Wei Zhou ◽  
Yang Shen ◽  
Ming-Lei Guo ◽  
...  
Keyword(s):  
Light Emitting ◽  
Light Emitting Devices ◽  
Luminescence Efficiency

Poly(Vinylidene Fluoride)-Passivated CsPbBr3 Perovskite Quantum Dots with Near-Unity Photoluminescence Quantum Yield and Superior Stability

2021 ◽  
Author(s):  
Lin Yang ◽  
Bowen Fu ◽  
Xu Li ◽  
Hao Chen ◽  
Lili Li
Keyword(s):  
Quantum Dots ◽  
Quantum Yield ◽  
Vinylidene Fluoride ◽  
Excellent Performance ◽  
Inorganic Perovskite ◽  
Photoluminescence Quantum Yield ◽  
Poly Vinylidene Fluoride ◽  
Perovskite Quantum Dots ◽  
Optoelectronic Applications ◽  
Pl Quenching

All inorganic perovskite quantum dots (QDs) have received great attention owing to their excellent performance in optoelectronic applications. However, they often suffer from the defect-related photoluminescence (PL) quenching and phase...

Organic-inorganic hybrid thin film light-emitting devices: interfacial engineering and device physics

2021 ◽  
Author(s):  
Chunxiu Zang ◽  
Mengxin Xu ◽  
Letian Zhang ◽  
Shihao Liu ◽  
Wenfa Xie
Keyword(s):  
Thin Film ◽  
Quantum Dots ◽  
Sandwich Structure ◽  
Device Physics ◽  
Hybrid Thin Film ◽  
Inorganic Hybrid ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Interfacial Engineering ◽  
Organic Light

Thin film light-emitting devices (LEDs) with sandwich structure, such as organic light emitting devices (OLEDs), quantum dots LEDs (QLEDs) and perovskite LEDs (PeLEDs), have attracted wide attentions because of their...

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.

Blue and green double band luminescent carbon quantum dots: Synthesis, origin of photoluminescence, and application in white light-emitting devices

2021 ◽  
Vol 118 (15) ◽  
pp. 153102
Author(s):  
Xifang Chen ◽  
Wenhui Wu ◽  
Wenxia Zhang ◽  
Ziye Wang ◽  
Zhenjin Fu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
White Light ◽  
Carbon Quantum Dots ◽  
Light Emitting ◽  
Light Emitting Devices

Photoluminescence Properties of Ca3Si2O7: Pr3+ Orange-Red Phosphors Prepared by High-Temperature Solid-State Method

2018 ◽  
Vol 73 (6) ◽  
pp. 555-558 ◽  
Author(s):  
Zhi-Qing Peng ◽  
Rong Chen ◽  
Wen-Lin Feng
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Solid State ◽  
Solid State Method ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Red Phosphors ◽  
Typical Sample ◽  
State Method ◽  
Xrd Patterns

AbstractNovel luminescent materials Ca3-xSi2O7: xPr3+ were successfully prepared by the high-temperature solid-state method. The crystal structure, morphology, and optical spectrum were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectroscopy, respectively. The XRD patterns of the samples indicate that the crystal structure is monoclinic symmetry. The SEM shows that the selected sample has good crystallinity although its appearance is irregular and scalelike. The peak of the excitation spectrum of the sample is located at around 449 nm, corresponding to 3H4→3P2 transition of Pr3+. The peak of the emission spectrum of the sample is situated at around 612 nm which is attributed to 3P0→3H6 transition of Pr3+, and the colour is orange-red. The optimum concentration for Pr3+ replaced Ca2+ sites in Ca3Si2O7: Pr3+ is 0.75 mol%. The lifetime (8.48 μs) of a typical sample (Ca2.9925Pr0.0075)Si2O7 is obtained. It reveals that orange-red phosphors Ca3-xSi2O7: xPr3+ possess remarkable optical properties and can be used in white light emitting devices.

The Effect of Particle Size on the Charge Balance Property of Quantum Dot Light-Emitting Devices Using Zinc Oxide Nanoparticles

2021 ◽  
Vol 21 (7) ◽  
pp. 3795-3799
Author(s):  
Mi-Young Ha ◽  
Chang Kyo Kim ◽  
Dae-Gyu Moon
Keyword(s):  
Particle Size ◽  
Zinc Oxide ◽  
Quantum Dot ◽  
Zinc Oxide Nanoparticles ◽  
Transport Layer ◽  
Oxide Nanoparticles ◽  
Zno Nps ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Maximum Current

Zinc oxide nanoparticles (ZnO NPs) have been widely used as an inorganic electron transport layer (ETL) in quantum dot light-emitting devices (QLEDs) due to their excellent electrical properties. Here, we report the effect of ZnO NPs inorganic ETL of different particle sizes on the electrical and optical properties of QLEDs. We synthesized ZnO NPs into the size of 3 nm and 8 nm respectively and used them as an inorganic ETL of QLEDs. The particle size and crystal structure of the synthesized ZnO NPs were verified by Transmission electron microscopy (TEM) analysis and X-ray pattern analysis. The device with 8 nm ZnO NPs ETL exhibited higher efficiency than the 3 nm ZnO NPs ETL device in the single hole transport layer (HTL) QLEDs. The maximum current efficiency of 19.0 cd/A was achieved in the device with 8 nm ZnO NPs layer. We obtained the maximum current efficiency of 17.5 cd/A in 3 nm ZnO NPs device by optimizing bilayer HTL and ZnO NPs ETL.

Improve the Efficiency of White Organic Light-Emitting Devices Using Double-Doped System

2010 ◽  
Vol 152-153 ◽  
pp. 687-690
Author(s):  
Gui Ying Ding ◽  
Wen Long Jiang ◽  
Guang De Wang ◽  
Qiang Han ◽  
Xi Chang
Keyword(s):  
Current Efficiency ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Organic Light ◽  
Maximum Current ◽  
Hole Transporting ◽  
White Oleds ◽  
Organic Light Emitting Devices ◽  
20 Nm ◽  
White Oled

The doped and non-doped white Organic light-emitting devices (OLEDs) were fabricated, using strong yellow emitting and hole-transporting ability of TPAHQZn. When the white OLED is a double-doped structure, greatly enhanced the efficiency of the device. The double-doped white device were fabricated as follows: ITO/2T-NATA (17 nm)/ CBP: 30% TPAHQZn: 8% Ir(ppy)3 (25 nm)/ NPBX (15 nm)/BCP(8nm)/TPBi: 10% Ir(ppy)3 (15nm)/Alq3 (20 nm)/LiF (1.3 nm)/Al. The double-doped white OLEDs were obtained with Commission International de L’Eclairage coordinates of (0.29,0.28) at 17 V, the maximum current efficiency increaed four times that double-doped white device of 4.12cd/A(8V) than non-doped of 1.03 cd/A (10V) .

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