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Low Power Consumption Red Light-Emitting Diodes Based on Inorganic Perovskite Quantum Dots under an Alternating Current Driving Mode
摘要： Inorganic perovskites have emerged as a promising candidate for light-emitting devices due to their high stability and tunable band gap. However, the power consumption and brightness have always been an issue for perovskite light-emitting diodes (PeLEDs). Here, we improved the luminescence intensity and decreased the current density of the PeLEDs based on CsPbI3 quantum dots (QDs) and p-type Si substrate through an alternating current (AC) driving mode. For the different driving voltage modes (under a sine pulsed bias or square pulsed bias), a frequency-dependent electroluminescent (EL) behavior was observed. The devices under a square pulsed bias present a stronger EL intensity under the same voltage due to less thermal degradation at the interface. The red PeLEDs under a square pulsed bias driving demonstrate that the EL intensity drop-off phenomenon was further improved, and the integrated EL intensity shows the almost linear increase with the increasing driving voltage above 8.5 V. Additionally, compared to the direct current (DC) driving mode, the red PeLEDs under the AC condition exhibit higher operating stability, which is mainly due to the reducing accumulated charges in the devices. Our work provides an effective approach for obtaining strong brightness, low power consumption, and high stability light-emitting devices, which will exert a profound in?uence on coupling LEDs with household power supplies directly.
关键词： low power consumption,perovskite quantum dots,silicon,light emitting diodes,alternating current driving
更新于2025-11-21 11:01:37
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P‐type Sb‐doped Cu <sub/>2</sub> O Hole Injection Layer Integrated on Transparent ITO Electrode for Acidic PEDOT:PSS‐Free Quantum Dot Light Emitting Diodes
摘要： It is developed that transparent p-type Sb-doped cuprous oxide (ACO) integrated Sn-doped In2O3 (ITO) film as hole injection layer (HIL) and anode combined electrodes for quantum dot light emitting diodes (QD-LEDs) to substitute acidic PEDOT:PSS HIL based electrode. By graded co-sputtering of ACO and ITO targets, the graded p-type ACO buffer layer can be integrated on the surface region of the ITO electrodes. P-type conductivity of the ACO film for acting as effective HIL in QD-LEDs is confirmed by a positive Hall coefficient (1.74 (cid:1) 10 (cid:3)1). Due to the well-matched work function of p-type ACO on the ITO electrodes, the acidic PEDOT:PSS-free QD-LEDs exhibited typical current-voltage-luminescence of QD-LEDs. The successful operation of PEDOT:PSS-free QD-LED with p-type ACO integrated ITO electrode indicates that ACO and ITO anode graded sputtering is simpler fabrication steps for cost-effective QD-LEDs and elimination of interfacial reactions caused by the acidic PEDOT:PSS layer for reliable QD-LEDs.
关键词： Sn-doped In2O3,acidic PEDOT:PSS,hole injection layer,p-type conductivity,Sb-doped Cu2O,quantum dots light emitting diodes
更新于2025-11-21 10:59:37
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Robust CsPbX <sub/>3</sub> (X = Cl, Br, and I) perovskite quantum dot embedded glasses: nanocrystallization, improved stability and visible full-spectral tunable emissions
摘要： Currently, all inorganic perovskite quantum dots (QDs) of cesium lead halides (CsPbX3, X = Cl, Br, and I) have been mainly fabricated using wet chemical methods. Unfortunately, applications of perovskite QDs have been limited due to their poor stability. In the present work, the in situ growth of whole-family CsPbX3 (X = Cl, Br, and I) perovskite QDs in Zn–P–B–Sb based oxide glass via a glass crystallization strategy is reported. The as-prepared CsPbX3 QDs@glass nanocomposites exhibit typical excitonic recombination emissions and superior chemical stability benefited from the protection of the robust inorganic glass matrix. Through modifying the molar ratio of halide sources in glass, multi-color tunable emissions in the entire visible spectral range of 400–750 nm are achieved. As a result, light-emitting diode devices can be constructed by coupling blue-emissive CsPbBrCl2, green-emissive CsPbBr3 and red-emissive CsPbBr0.5I2.5 QDs@glass powders with a commercial ultraviolet chip, yielding bright white light luminescence with excellent optoelectronic performance.
关键词： stability,light-emitting diodes,tunable emissions,glass crystallization,perovskite quantum dots
更新于2025-11-20 15:33:11
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Efficient White LEDs Using Liquid-state Magic-sized CdSe Quantum Dots
摘要： Magic clusters have attracted significant interest to explore the dynamics of quantum dot (QD) nucleation and growth. At the same time, CdSe magic-sized QDs reveal broadband emission in the visible wavelength region, which advantageously offer simple integration of a single-type of nanomaterial and high color rendering ability for white light-emitting diodes (LEDs). Here, we optimized the quantum yield of magic-sized CdSe QDs up to 22% via controlling the synthesis parameters without any shelling or post-treatment process and integrated them in liquid-state on blue LED to prevent the efficiency drop due to host-material effect. The fabricated white LEDs showed color-rendering index and luminous efficiency up to 89 and 11.7 lm/W, respectively.
关键词： Magic clusters,Quantum dots,Luminous efficiency,CdSe,White light-emitting diodes
更新于2025-11-20 15:33:11
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Synthesis, Photophysical and Electroluminescent Properties of Iridium(III) Complexes with 2-Aryl-thiazole and Oxadiazol-substituted Amide Derivative Ligands
摘要： By using aryl-thiazole as cyclometalated ligand and oxadiazol-substituted amide as ancillary ligand, three novel iridium(III) complexes have been synthesized and characterized, and the photophysical and electrochemical properties have been investigated. Complexes 1–3 exhibit efficient phosphorescence emissions at 542, 555 and 585 nm with photoluminescence quantum yields (PLQYs) of 0.04, 0.03 and 0.02 in CH3CN solutions, respectively. In the 10 wt% doped 2,4-diphenyl-6-bis(12-phenylindolo)[2,3-a]carbazole-11-yl)-1,3,5-triazine (Dictrz) film, the PLQYs (0.88 for complex 1, 0.47 for complex 2 and 0.37 for complex 3) increase significantly owing to the great restriction of rotations and vibrations in rigid host. The organic light-emitting diodes based on these complexes show good performance with the maximum current efficiencies of 20.06, 22.20 and 13.45 cd A-1 and maximum power efficiencies of 13.54, 17.31 and 9.48 lm W?1 with the CIE coordinates of (0.46, 0.53), (0.49, 0.50) and (0.59, 0.40) for complexes 1?3, respectively.
关键词： Iridium complex,Aryl-thiazole,Organic light-emitting diodes,Oxadiazol-substituted amide
更新于2025-11-19 16:56:35
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - A Synthetic Method for Extremely Stable Thin Film of CsPbBr<inf>3</inf> QDs and its Application on Light-emitting Diodes
摘要： The ability to be mixed with the polymers is very important for applications of perovskite quantum dots (QDs), such as in display, lighting and so on. Here, a method for fabricating a thin film composed of CsPbBr3 QDs and polydimethylsiloxane (PDMS) was reported. By using the ethyl acetate, a large number of ligands on the surface were removed and the combination with polymers can realize. Based on the thin film, an LED device was assembled and its luminous flux, luminous efficiency, color temperature and CIE color coordinates were measured. What’s more, the thin film revealed a splendid stability after being stored for 42 days without any protection, which show the broad prospects of it.
关键词： Inorganic perovskite quantum dots,Stability,Light-emitting diodes
更新于2025-11-19 16:46:39
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Electrochemical capacitance-voltage profiling of nonuniformly doped GaAs heterostructures with SQWs and MQWs for LED applications
摘要： Light-emitting heterostructures with single and multiple GaAs/InGaAs quantum wells have been investigated by means of electrochemical capacitance-voltage (ECV) profiling. Capacitance-voltage characteristics were measured; concentration profiles of free charge carriers over the heterostructure depth as well as the intensity of quantum well filling by charge carriers were obtained. In heterostructures with a single quantum well (QW) we considered limitations of capacitance techniques for undoped QW profiling, which is situated near the metallurgic border of the p–n –junction. We made a detailed consideration of phenomena related to Debye smearing and we developed and analyzed the dependence of the space charge region width on the doping. Special attention was paid to investigation of the “blind” area. This was inspired by the practical problem from capacitance spectroscopy of semiconductors, when the researcher poses the task of obtaining a free charge carrier depth distribution profile as deep as possible in the space charge region, i.e. where the intensity of the electric field is maximum. Generally, the active QW of a LED heterostructure is placed deep in the space charge region, so reaching these regions is extremely important for practical problems. We present an evolution of capacitance-voltage characteristics during ECV profiling of nonuniformly doped p – n– heterostructures. For a heterostructure with multiple quantum wells we registered a response from 6 QWs.
关键词： capacitance-voltage profiling,heterostructure,quantum well,nonuniform doping,Electrochemical capacitance-voltage profiling,quantum dot,light-emitting diodes
更新于2025-11-14 17:28:48
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Facile microwave synthesis of carbon dots powder with enhanced solid-state fluorescence and its applications in rapid fingerprints detection and white-light-emitting diodes
摘要： In this report, we successfully developed a simple and fast MW-assisted method for preparing CDs with strong solid-state fluorescence (SSF) by using phthalic acid and piperazine as precursors. The prepared p-CDs can be obtained in high yield (48.7%) and emit bright yellow-green SSF under 365 nm UV light. The absolute PL quantum yield (PLQY) of p-CDs in solid state was measured to be 20.5%, which is much higher than that in aqueous solution. This interesting phenomenon shows that p-CDs not only successfully conquer the aggregation-caused fluorescence quenching (ACQ) effect, but also achieve enhanced fluorescence emission, which was rarely reported in previous literatures as CDs in solid state always reduce their fluorescence emission due to the excessive resonance energy transfer (RET) or direct π-π interactions. In addition, the relationship between the feed ratio of precursors and optical properties of the CDs were also investigated detailedly. Based on their strong SSF, the p-CDs were successfully used in rapid latent fingerprints detection and white light-emitting diodes (WLEDs) preparation with high quality. In summary, this research not only developed a new type of CDs with strong enhanced SSF, but also offered a valuable reference for design SSF-emitting CDs with high yield.
关键词： Carbon dots,Solid-state fluorescence,Light-emitting diodes,Latent fingerprints
更新于2025-11-14 17:04:02
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Novel hole blocking materials based on 2,6-disubstituted dibenzo[ <i>b</i> , <i>d</i> ]furan and dibenzo[ <i>b</i> , <i>d</i> ]thiophene segments for high-performance blue phosphorescent organic light-emitting diodes
摘要： Novel hole blocking materials (HBMs) based on 2,6-disubstituted dibenzo[b,d]furan and dibenzo[b,d]thiophene segments, 3,30,300,30 0 0-(dibenzo[b,d]furan-2,6-diylbis(benzene-5,3,1-triyl))tetrapyridine (26DBFPTPy) and 3,30,300,30 0 0-(dibenzo[b,d]thiophene-2,6-diylbis(benzene-5,3,1-triyl))tetrapyridine (26DBTPTPy), are successfully designed and synthesized for high-performance blue phosphorescent organic light-emitting diodes (PhOLEDs) for the first time. Computational simulation is used to investigate the optimal structure, orbital distribution, and physicochemical properties of both molecules. Thermal, optical, and electrochemical analysis shows that 26DBFPTPy and 26DBTPTPy possess high thermal stability, deep HOMO energy levels ((cid:2)7.08 and (cid:2)6.91 eV), and a high triplet energy (ET) (2.75 and 2.70 eV). Blue PhOLEDs with 26DBFPTPy or 26DBTPTPy as a hole blocking layer (HBL) exhibit a low turn-on voltage (3.0 V) and operating voltage (4.5 V) at 1000 cd m(cid:2)2. In addition, the blue PhOLEDs with 26DBFPTPy or 26DBTPTPy show superior external quantum e?ciencies (24.1 and 23.6%) and power e?ciencies (43.9 and 42.7 lm W(cid:2)1). They also show a very small e?ciency roll-o? of about 8.5% from 100 to 1000 cd m(cid:2)2. Furthermore, they exhibit improved lifetimes compared to the similarly designed HBL with a pyridine electron transport unit and a phenyl core structure.
关键词： dibenzo[b,d]furan,hole blocking materials,dibenzo[b,d]thiophene,blue phosphorescent organic light-emitting diodes,high-performance
更新于2025-11-14 15:32:45
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Ultrathin, Core–Shell Structured SiO <sub/>2</sub> Coated Mn <sup>2+</sup> ‐Doped Perovskite Quantum Dots for Bright White Light‐Emitting Diodes
摘要： All-inorganic semiconductor perovskite quantum dots (QDs) with outstanding optoelectronic properties have already been extensively investigated and implemented in various applications. However, great challenges exist for the fabrication of nanodevices including toxicity, fast anion-exchange reactions, and unsatisfactory stability. Here, the ultrathin, core–shell structured SiO2 coated Mn2+ doped CsPbX3 (X = Br, Cl) QDs are prepared via one facile reverse microemulsion method at room temperature. By incorporation of a multibranched capping ligand of trioctylphosphine oxide, it is found that the breakage of the CsPbMnX3 core QDs contributed from the hydrolysis of silane could be effectively blocked. The thickness of silica shell can be well-controlled within 2 nm, which gives the CsPbMnX3@SiO2 QDs a high quantum yield of 50.5% and improves thermostability and water resistance. Moreover, the mixture of CsPbBr3 QDs with green emission and CsPbMnX3@SiO2 QDs with yellow emission presents no ion exchange effect and provides white light emission. As a result, a white light-emitting diode (LED) is successfully prepared by the combination of a blue on-chip LED device and the above perovskite mixture. The as-prepared white LED displays a high luminous efficiency of 68.4 lm W?1 and a high color-rendering index of Ra = 91, demonstrating their broad future applications in solid-state lighting fields.
关键词： quantum dots,white light-emitting diodes,core–shells,Mn2+-doping,SiO2-coating
更新于2025-11-14 15:32:45