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High Efficiency Quantum Dot Light-Emitting Diode by Solution Printing of Zinc Oxide Nanoparticles
摘要： Quantum dot light-emitting diodes (QLEDs) have attracted considerable attention owing to the narrow emission spectra, wide color gamut, high quantum yield and size-controlled emission wavelength. Zinc oxide nanoparticles have been widely used as an electron transport layer (ETL) in QLEDs due to their excellent electrical properties. In this study, we compared the efficiency of QLEDs with organic and zinc oxide ETLs in viewpoint of the charge balance. The QLEDs were constructed using ZnO nanoparticles with an average particle size of 3 nm or 3TPYMB as the ETL materials. CdSe/ZnS quantum dots and poly-TPD were used as a light-emitting elements and hole transporting material, respectively. The QLED with 3TPYMB ETL exhibited current efficiency of 7.71 cd/A, while the efficiency of the QLED using ZnO nanoparticles was significantly improved to 38.76 cd/A. Such a substantial improvement of emission efficiency in the QLEDs with ZnO ETL was attributed to the much better charge balance by the ZnO.
关键词： Solution Printing,Zinc Oxide Nanoparticles,Quantum Dot Light-Emitting Diode
更新于2025-09-19 17:13:59
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All-solution processed inverted QLEDs with double hole transport layers and thermal activated delay fluorescent dopant as energy transfer medium
摘要： Highly efficient, all-solution processed inverted quantum dot light-emitting diodes (QLEDs) with high performance are demonstrated by employing poly(9-vinlycarbazole) (PVK) as additional hole transport layer (HTL) and doping it with a blue thermal activated delay fluorescent (TADF) material, 4,5-bis(carbazol-9-yl)-1,2-dicyanobenzene (2CzPN). This PVK: 2CzPN composite layer not only optimizes hole injection, but also utilizes the leaked electrons to enhance device luminance by energy transfer process from 2CzPN to quantum dots (QDs). These benefits enable a 20-fold increment for the device current efficiency (from 0.523 cd/A to 11 cd/A) and a 9.9-fold improvement for the maximum luminance (from 3220 cd/m2 to 35352 cd/m2), compared with those of the standard QLED with poly[(9, 9-dioctylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-butylphenyl) (TFB) single HTL. In comparison with the QLED with TFB/pristine PVK double HTLs, the device performance of the optimal QLED with PVK: 2CzPN additional HTL are still 40.8% and 61.7% higher in luminance and current efficiency, respectively.
关键词： Thermally activated delayed fluorescence,Quantum dot light-emitting diode,All-solution process,Energy transfer,Double hole transport layers,Inverted structure
更新于2025-09-12 10:27:22
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Equivalent Circuit of Quantum-Dot LED and Acquisition of Carrier Lifetime in Active Layer
摘要： We propose an equivalent circuit for a quantum-dot LED (QLED), where the resistances and the capacitances are expressed in terms of the physical parameters of the QLED. The validity of the equivalent circuit is verified by measurement results. From the measured frequency response of the QLED and the calculated frequency response of the equivalent circuit, we are able to deduce the carrier lifetime in the active layer of the QLED. The availability of the equivalent circuit can facilitate the analysis of the electrical characteristics of QLEDs.
关键词： Quantum-dot light-emitting diode,frequency response,carrier lifetime,equivalent circuit
更新于2025-09-12 10:27:22
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[IEEE 2019 International conference on Creative Business for Smart and Sustainable Growth (CREBUS) - Sandanski, Bulgaria (2019.3.18-2019.3.21)] 2019 International Conference on Creative Business for Smart and Sustainable Growth (CREBUS) - Innovative LED Lighting
摘要： The main innovative technologies and the principle of operation of OLED, FOLED, PHOLED, TOLED, QLED and RGB diodes are examined in this work. Luminous efficiency and the operating time dependencies on the working temperature of the diode are presented. The highly efficient light sources presented are also considered from the point of view of their energy use: for their production, use and subsequent safe disposal. In this way, an economic and environmental assessment of the benefits of their use in industry and households has been made.
关键词： Light-Emitting Diode,Efficiency,Quantum dot light emitting diode,Organic Light Emitting Diode
更新于2025-09-11 14:15:04
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Synthesis of Alloyed ZnSeTe Quantum Dots as Bright, Color-Pure Blue Emitters
摘要： Considering a strict global environmental regulation, fluorescent quantum dots (QDs) as key visible emitters in the next-generation display field should be compositionally non-Cd. When compared to green and red emitters obtainable from size-controlled InP QDs, development of non-Cd blue QDs remains stagnant. Herein, we explore synthesis of non-Cd, ZnSe-based QDs with binary and ternary compositions toward blue photoluminescence (PL). First, size increment of binary ZnSe QDs is attempted by a multiply repeated growth until blue PL is attained. Although this approach offers a relevant blue color, excessively large-sized ZnSe QDs inevitably entail a low PL quantum yield (QY). As an alternative strategy to the above size enlargement the alloying of high-band gap ZnSe with lower-band gap ZnTe in QD synthesis is carried out. These alloyed ternary ZnSeTe QDs after ZnS shelling exhibit systematically tunable PL of 422?500 nm as a function of Te/Se ratio. Analogous to state-of-the-art heterostructure of InP QDs with a double-shelling scheme, an inner shell of ZnSe is newly inserted with different thicknesses prior to an outer shell of ZnS, where the effects of the thickness of ZnSe inner shell on PL properties are examined. Double-shelled ZnSeTe/ZnSe/ZnS QDs with an optimal thickness of ZnSe inner shell are then employed for all-solution-processed fabrication of blue QD-light-emitting diode (QLED). The present blue QLED as the first ZnSeTe QD-based device yields a peak luminance of 1195 cd/m2, current efficiency of 2.4 cd/A, and external quantum efficiency of 4.2%, corresponding to the record values reported from non-Cd blue devices.
关键词： external quantum efficiency,alloyed ZnSeTe quantum dots,Non-Cd blue emitters,ZnSe inner shell,quantum dot-light-emitting diode
更新于2025-09-11 14:15:04
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Optimization of a Solution-Processed Quantum-Dot Light-Emitting-Diode with an Inverted Structure
摘要： Colloidal quantum-dot based light-emitting diodes (QD-LEDs) are attractive for use in display devices because of the remarkable electrical and optical characteristics of colloidal quantum dots. An inverted structure may be one method to achieve the necessary multilayer device structures in QD-LEDs. In this study, each layer of an inverted-structure QD-LED was optimized. The effect of the solvent on the hole transfer layer was investigated, along with the effect of the concentration of the electron transfer layer, the effect of the co-solvent on the hole transfer layer, and the effect of the concentration and solvent of quantum dot layer. The quantum dots and ZnO NPs were synthesized as the emitting layer and carrier transporting layer using a solution-mediated process. The inverted QD-LED device showed a luminance of 3,762 cd/m2, current ef?ciency of 1.86 cd/A, and EQE of 1.18%.
关键词： Inverted Structure,Solution-Process,Quantum Dot Light Emitting Diode (QD-LED)
更新于2025-09-04 15:30:14