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Higha??efficiency quantum dot lighta??emitting diodes with blue cadmiuma??free quantum dots
摘要： We report outstanding electroluminescence properties of high-efficiency blue cadmium-free quantum dot light-emitting diodes (QD-LED). External quantum efficiency (EQE) of 14.7% was achieved for QD-LED emitting at 428 nm. Furthermore, we developed high-efficiency and narrow wavelength emission zinc selenide (ZnSe) nanocrystals emitting at 445 nm and achieved QD-LED with an EQE of 10.7%. These new QDs have great potential to be used in next-generation QD-LED display with wide color gamut.
关键词： cadmium-free,blue quantum dot,QD-LED,EQE
更新于2025-09-23 15:21:01
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Double Metal Oxide Electron Transport Layers for Colloidal Quantum Dot Light-Emitting Diodes
摘要： The performance of colloidal quantum dot light-emitting diodes (QD-LEDs) have been rapidly improved since metal oxide semiconductors were adopted for an electron transport layer (ETL). Among metal oxide semiconductors, zinc oxide (ZnO) has been the most generally employed for the ETL because of its excellent electron transport and injection properties. However, the ZnO ETL often yields charge imbalance in QD-LEDs, which results in undesirable device performance. Here, to address this issue, we introduce double metal oxide ETLs comprising ZnO and tin dioxide (SnO2) bilayer stacks. The employment of SnO2 for the second ETL significantly improves charge balance in the QD-LEDs by preventing spontaneous electron injection from the ZnO ETL and, as a result, we demonstrate 1.6 times higher luminescence efficiency in the QD-LEDs. This result suggests that the proposed double metal oxide ETLs can be a versatile platform for QD-based optoelectronic devices.
关键词： metal oxide,light emitting diode (LED),SnO2 nanoparticles,quantum dot (QD),double electron transport layer (ETL)
更新于2025-09-23 15:19:57
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Thermal Impact of LED Chips on Quantum Dots in Remote-Chip and On-Chip Packaging Structures
摘要： Light-emitting diode (LED) chips in quantum dot (QD)-converted LEDs serve simultaneously as a heat source and a heat sink, but it remains unclear which of these is the major factor that affects the operating temperature of QDs. Here, we investigated the thermal and optical performances of QD-converted LEDs using QD-on-chip and QD-remote-chip packaging structures, to better understand the thermal effect of LED chips on QDs. Our results indicated that the QD-on-chip structure achieved the same optical performance as the QD-remote-chip structure, while the former can save QD usage up to 75.9% owing to the higher absorption probability of QDs closer to the blue source. Most importantly, the QD-on-chip structure largely reduced the maximal surface temperature from 82.7 ?C to 60.2 ?C at 250 mA, and had a longer operating lifetime compared with the QD-remote-chip structure. Simulations revealed that the QD-remote-chip structure could suppress the heat transfer from chips to QDs; however, the hot spot remained in QDs, owing to the heavy conversion loss and low thermal conductivity of the silicone matrix; consequently, the QD-on-chip structure had better heat dissipation (lower temperature) for QDs closer to the chip that served as heat sinks. Therefore, it is suggested to place QDs near the heat sink with high thermal conductivity, such as the LED chip, for heat dissipation; this is better than removing QDs for blocking the heat generated by the LED chip.
关键词： Light-emitting diodes (LEDs),quantum dot (QD),packaging structure,thermal and optical performance
更新于2025-09-16 10:30:52
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Influence of Quantum Dot Characteristics on the Performance of Hybrid SET-FET Circuits
摘要： Quantum dots (QDs) can be used as conductive islands to build-up single-electron transistors (SETs). The characteristics of the QDs define the functional performance of the SETs. In consequence, analyzing the influence of the variations of QD dimensions on the performance of hybrid SET-FET circuits is of high relevance. We employ a self-developed SET compact model which is calibrated to 3-D quantum-mechanics-based simulations in order to obtain realistic model parameters. A method to improve the circuit behavior, i.e., to increase the output current, is proposed. It is concluded that the variation of the QD size presents the largest influence on the overall circuit behavior.
关键词： variability,single-electron transistor (SET),quantum dot (QD),Nanowires
更新于2025-09-11 14:15:04
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Ruthenium decorated tungsten disulfide quantum dots for CO2 gas sensor
摘要： In this work, a selective chemi-resistive gas sensor for carbon dioxide gas detection at room temperature (~ 25 °C) was successfully fabricated, where ruthenium decorated tungsten disulfide (Ru@WS2) quantum dots (QDs) have been used as the sensing material. A mixed solvent of lithium hydroxide (LiOH·H2O) and N-Methyl-2-pyrrolidone (NMP) were used to obtain the Ru decorated WS2 QD from the exfoliated WS2 nanoflakes. Then the prepared WS2 QD and Ru@WS2 QD were confirmed using different material characterisation techniques. The gas sensors were then exposed to various concentration of CO2 gas in dry air condition. Also, the effect of humidity of both the sensors in 5000 ppm CO2 gas has been studied. The Ru@WS2 QDs based sensor showed superior sensitivity and good selectivity to CO2 gas in comparison with isopropanol, acetone, ethanol, methanol and benzene at room temperature than WS2 QD. The sensor showed an increase in resistance when exposed to CO2 gas ranging from 500 to 5000 ppm, indicating p-type characteristics. Ru@WS2 QD shows less effect at different humid condition compares to WS2 QD as a CO2 gas sensor.
关键词： Ruthenium decorated tungsten disulfide (Ru@WS2),Transition metal dichalcogenides (TMDC),Quantum Dot (QD),Sensitivity,Selectivity,Gas sensor
更新于2025-09-11 14:15:04