面向显示应用的量子点发光器件研究进展

胶体量子点是一种半径接近于激子玻尔半径的新型优质光电材料,其特殊的尺寸效应使其能通过调整尺寸大小实现高纯度的三原色发光、连续可调的光谱以及宽色域.量子点特殊的核壳结构保证了其良好的光/热稳定性;同时,量子点还具有优异的可溶液处理特性,是显示领域研究的热门材料.基于量子点构筑的量子点发光二极管器件也一直被看作是有望取代有...     

室温合成的钙钛矿量子点及其电致发光二极管

采用室温合成法制备出CsPbBr3钙钛矿量子点,并采用乙酸乙酯对量子点进行了一次、二次和三次清洗,以控制其表面配体密度。然后,利用合成并经过清洗的钙钛矿量子点制备了结构为ITO/PEDOT∶PSS/PTAA/CsPbBr3 QD/TPBi/LiF/Al的电致发光二极管(QLED)。研究了经不同清洗次数的量子点材料制备的器件的光电性能。结果表明,清洗2次的量子点在电荷注入与溶液稳定性之间得到平衡,利用其制备的钙钛矿QLED获得了最大亮度为1405cd/m²、外量子效率为0.6%、色坐标为(0.127,0.559)的绿光发射。     

量子点发光显示器件

量子点发光二极管（QD—LEDs）是将有机小分子OLED与可发光无机量子点（QD）结合起来而形成的一种新技术。量子点LED既具有聚合物的可溶性，容易制造的优点。同时还具有潜在的类似于磷光材料的高发光效率。     

钙钛矿量子点玻璃背光应用

随着人们生活水平和社会经济的提升,对具有优良显色性和色彩再现力的液晶显示器的需求急剧增加。然而,商业使用的传统稀土掺杂的荧光粉转光层由于发射半峰宽太宽已经无法满足宽色域显示的需求,因此迫切需要开发一种新材料以实现宽色域显示。钙钛矿量子点玻璃因其优异的光学性能与卓越的稳定性被认为是背光显示器中传统荧光粉转光层的理想替代品,在显示行业具有广泛的应用前景。本文综述了钙钛矿量子点玻璃背光结构的应用方式,并对近年来钙钛矿量子点玻璃在背光应用的研究现状与发展中所面临的挑战进行了概括,最后对其进行了展望。     

量子点及量子点器件

量子点是纳米科学与技术研究重要的组成部分,量子点器件又是纳米器件的发展方向之一.详细介绍了量子点的分类、量子点的主要制备方式、量子点特性的传统研究和微波类比仿真研究方法,系统论述了量子点器件的分类应用及噪声抑制.     

量子点发光在显示器件中的应用

介绍了量子点材料的发光原理、基本结构,以及量子点LED的特性、制备方法以及其在显示领域的最新进展。量子点LED由于具有发光纯度高、使用寿命长、可由溶液法制备等独特的优点,越来越受到人们的重视,成为显示领域新的研究热点。     

聚合物钝化钙钛矿量子点的红光放大自发辐射性能

全无机CsPbX₃(X=Cl、Br、I)钙钛矿量子点具有优异的发光性能,是一种极具应用潜力的新型显示材料及激光增益介质。本文制备了发光峰位于640 nm的CsPbBr_1.2I_1.8红光量子点,在该量子点薄膜表面分别涂覆聚甲基丙烯酸甲酯(PMMA)、聚甲基丙烯酸异丁酯(PIBMA)、聚苯乙烯(PS)3种带不同功能基团的聚合物,制备了CsPbBr_1.2I_1.8/PMMA、CsPbBr_1.2I_1.8/PIBMA、CsPbBr_1.2I_1.8/PS复合薄膜,研究它们的放大自发辐射性能。结果表明,聚合物钝化一方面提升了量子点的水稳定性,另一方面,PMMA和PIBMA中的C=O钝化了量子点表面未配位的Pb²⁺,增强了量子点薄膜的光致发光强度。进一步的,在532 nm的纳秒激光泵浦下,CsPbBr_1.2I_1.8/PIBMA薄膜放大自发辐射阈值...     

基于锗量子点的硅基发光器件

硅基光源是实现硅基集成光电子芯片的核心器件,虽然近年来国内外已经取得多项重要成果,但适合于下一代大规模光电集成芯片的小尺寸、低功耗、工艺兼容的高效硅基发光器件仍然缺乏。文章介绍了基于嵌入光学微腔中的锗量子点实现硅基发光器件方面的研究成果,通过将分子束外延生长的锗自组装量子点嵌入硅光子晶体微腔中,实现了室温下处于通信波段的共振发光。通过在图形化衬底上生长实现锗量子点的定位,并精确嵌入光子晶体微腔中,实现了基于锗单量子点的硅基发光器件。     

量子点发光器件的制备与仿真分析

为研究量子点发光器件结构与性能的关系,制备了以CdSe/ZnS量子点作为发光层、poly-TPD作为空穴传输层,Alq3作为电子传输层的量子点发光二极管,对器件结构及性能参数进行了表征,结果显示器件具有开启电压低、色纯度高等特点.结合测试数据,对量子点发光二极管进行了器件结构建模,利用隧穿模型及空间电荷限制电流模型对实验结果进行了分析,研究了器件中载流子的注入与传输机理.器件测试与仿真结果表明:各功能层厚度会影响载流子在量子点层的注入平衡,同时器件中载流子的注入与传输存在一转变电压,当外加电压低于转变电压时,器件中载流子的注入主要符合隧穿模型;当外加电压高于转变电压时,器件中载流子的注入主要符合空间电荷限制电流模型.研究结果验证了器件结构建模的合理性,可以利用仿真的方法进行器件结构优化并确定相关参数,这对器件性能的提高具有指导意义.     

Enhanced Photoluminescence and Photoresponsiveness of Eu3+ Ions-Doped CsPbCl3 Perovskite Quantum Dots under High Pressure

Metal halide perovskite quantum dots (QDs) have garnered tremendous attention in optoelectronic devices owing to their excellent optical and electrical properties. However, these perovskite QDs are plagued by pressure-induced photoluminescence (PL) quenching, which greatly restricts their potential applications. Herein, the unique optical and electrical properties of Eu³⁺-doped CsPbCl₃ QDs under high pressure are reported. Intriguingly, the PL of Eu³⁺ ions displays an enhancement with pressure up to 10.1 GPa and still preserves a relatively high intensity at 22 GPa. The optical and structural analysis indicates that the sample experiences an isostructural phase transition at approximately 1.53 GPa, followed by an amorphous state evolution, which is simulated and confirmed through density functional theory calculations. The pressure-induced PL enhancement of Eu³⁺ ions can be associated with the enhanced energy transfer rate from excitonic state to Eu³⁺ ions. The photoelectric performance is enhanced by compression and can be preserved upon the release of pressure, which is attributed to the decreased defect density and increased carrier mobility induced by the high pressure. This work enriches the understanding of the high-pressure behavior of rare-earth-doped luminescent materials and proves that high pressure technique is a promising way to design and realize superior optoelectronic materials.     

Suppressing Ion Migration of Mixed-Halide Perovskite Quantum Dots for High Efficiency Pure-Red Light-Emitting Diodes

Perovskite-based light-emitting diodes (PeLEDs) with a mixed halide composition can be used to obtain the “pure red” emission, i.e., in the 620–650 nm range, required for high-definition displays. However, fast halide ion migration induces phase separation in these materials under electric fields, resulting in poor spectral stability and low efficiency. Herein, a method for producing mixed halide CsPbI_3-xBr_x quantum dots (QDs) is reported in which ion migration is suppressed. The mixed halide composition is first achieved by anion exchange between CsPbI₃ QDs and hydrobromic acid (HBr), during that the bromine ions efficiently passivate the iodine vacancies of the QDs. The original oleic acid ligands are then exchanged for 1-dodecanethiol (1-DT), which suppresses halide ion migration via the strong binding of the sulfhydryl group with the QD surface. PeLEDs based on these QDs exhibit a pure-red electroluminescence (EL) peak at 637 nm, a maximum external quantum efficiency (EQE) of 21.8% with an average value of 20.4%, a peak luminance of 2653 cd m⁻², and low EQE decease with increasing luminance. The EL spectrum of these devices is stable even at 6.7 V and they have an EQE half-life of 70 min at an initial luminance of 150 cd m⁻².     

All‐Inorganic Bismuth‐Based Perovskite Quantum Dots with Bright Blue Photoluminescence and Excellent Stability

Lead halide perovskite quantum dots (QDs) possess color‐tunable and narrow‐band emissions and are very promising for lighting and display applications, but they suffer from lead toxicity and instability. Although lead‐free Bi‐based and Sn‐based perovskite QDs (CsSnX₃, Cs₂SnX₆, and (CH₃NH₃)₃Bi₂X₉) are reported, they all show low photoluminescence quantum yield (PLQY) and poor stability. Here, the synthesis of Cs₃Bi₂Br₉ perovskite QDs with high PLQY and excellent stability is reported. Via a green and facile process using ethanol as the antisolvent, as‐synthesized Cs₃Bi₂Br₉ QDs show a blue emission at 410 nm with a PLQY up to 19.4%. The whole series of Cs₃Bi₂X₉ (X = Cl, Br, and I) QDs by mixing precursors can cover the photoluminescence emission range from 393 to 545 nm. Furthermore, Cs₃Bi₂Br₉ QDs show excellent photostability and moisture stability due to the all‐inorganic nature and the surface passivation by BiOBr, which enables the one‐pot synthesis of Cs₃Bi₂Br₉ QD/silica composite. A lead‐free perovskite white light‐emitting diode is fabricated by simply combining the composite of Cs₃Bi₂Br₉ QD/silica with Y₃Al₅O₁₂ phosphor. As a new member of lead‐free perovskite QDs, Cs₃Bi₂Br₉ QDs open up a new route for the fabrication of optoelectronic devices due to their excellent stability and photophysical characteristics.     

Facile Room‐Temperature Anion Exchange Reactions of Inorganic Perovskite Quantum Dots Enabled by a Modular Microfluidic Platform

In an effort to produce the materials of next‐generation photoelectronic devices, postsynthesis halide exchange reactions of perovskite quantum dots are explored to achieve enhanced bandgap tunability. However, comprehensive understanding of the multifaceted halide exchange reactions is inhibited by their vast relevant parameter space and complex reaction network. In this work, a facile room‐temperature strategy is presented for rapid halide exchange of inorganic perovskite quantum dots. A comprehensive understanding of the halide exchange reactions is provided by isolating reaction kinetics from precursor mixing rates utilizing a modular microfluidic platform, Quantum Dot Exchanger (QDExer). The effects of ligand composition and halide salt source on the rate and extent of the halide exchange reactions are illustrated. This fluidic platform offers a unique time‐ and material‐efficient approach for studies of solution phase‐processed colloidal nanocrystals beyond those studied here and may accelerate the discovery and optimization of next‐generation materials for energy technologies.     

多层InAs量子点的光致发光研究

采用MBE设备生长了多层InAs/GaAs量子点结构,测量了其变温光致发光谱和时间分辨光致发光谱.结果表明多层量子点结构有利于减小发光峰的半高宽,并且可以提高发光峰半高宽和发光寿命的温度稳定性.实验发现,加InGaAs盖层后,量子点发光峰的半高宽进一步减小,最小达到23.6 meV,并且发光峰出现红移.原因可能在于InGaAs盖层减小了InAs岛所受的应力,阻止了In组分的偏析,提高了InAs量子点尺寸分布的均匀性和质量,导致载流子在不同量子点中的迁移效应减弱.     

Amine‐Free Synthesis of Cesium Lead Halide Perovskite Quantum Dots for Efficient Light‐Emitting Diodes

Cesium lead halide perovskite quantum dots (PQDs) have attracted significant interest for optoelectronic applications in view of their high brightness and narrow emission linewidth at visible wavelengths. A remaining challenge is the degradation of PQDs during purification from the synthesis solution. This is attributed to proton transfer between oleic acid and oleylamine surface capping agents that leads to facile ligand loss. Here, a new synthetic method is reported that enhances the colloidal stability of PQDs by capping them solely using oleic acid (OA). Quaternary alkylammonium halides are used as precursors, eliminating the need for oleylamine. This strategy enhances the colloidal stability of OA capped PQDs during purification, allowing us to remove excess organic content in thin films. Inverted red, green, and blue PQD light‐emitting diodes (LED) are fabricated for the first time with solution‐processed polymer‐based hole transport layers due to higher robustness of OA capped PQDs to solution processing. The blue and green LEDs exhibit threefold and tenfold improved external quantum efficiency (EQE), respectively, compared to prior related reports for amine/ammonium capped cross‐linked PQDs. The brightest blue LED based on all inorganic CsPb(Br_1?xCl_x)₃ PQDs is also reported.     

Saturated and Multi‐Colored Electroluminescence from Quantum Dots Based Light Emitting Electrochemical Cells

Novel light emitting electrochemical cells (LECs) are fabricated using CdSe‐CdS (core‐shell) quantum dots (QDs) of tuned size and emission blended with polyvinylcarbazole (PVK) and the ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIM‐PF₆). The performances of cells constructed using sequential device layers of indium tin oxide (ITO), poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS), the QD/PVK/IL active layer, and Al are evaluated. Only color saturated electroluminescence from the QDs is observed, without any other emissions from the polymer host or the electrolyte. Blue, green, and red QD‐LECs are prepared. The maximum brightness (≈1000 cd m^‐2) and current efficiency (1.9 cd A^‐1) are comparable to polymer LECs and multilayer QD‐LEDs. White‐light QD‐LECs with Commission Internationale d'Eclairage (CIE) coordinates (0.33, 0.33) are prepared by tuning the mass ratio of R:G:B QDs in the active layer and voltage applied. Transparent QD‐LECs fabricated using transparent silver nanowire (AgNW) composites as the cathode yield an average transmittance greater than 88% over the visible range. Flexible devices are demonstrated by replacing the glass substrates with polyethylene terephthalate (PET).     

Design and Synthesis of Fluorinated Quantum Dots for Efficient and Stable 0D/3D Perovskite Solar Cells

Dimensionality engineering involving the low-dimensional and 3D perovskites has been demonstrated as an efficient promising strategy to modulate interfacial energy loss as well as instability in perovskite solar cells (PSCs). Herein, the use of fluorinated Cesium Lead Iodide (CsPbI₃) perovskite quantum dot (PQD) is first reported as interface modification layer for PSCs. The binding between the CsPbI₃ PQD surface and native oleic acid (OLA)/oleylamine (OAm) ligands is governed by a dynamic adsorption–desorption equilibrium. Perfluorooctanoic acid (PFA) with stronger binding affinity and more hydrophobic nature is explored to partially replace OLA to prepare the fluorinated ligand capped CsPbI₃ PQDs (F-CsPbI₃). Through optimization of the addition of PFA during hot-injection synthesis, the in situ treated F-CsPbI₃ PQDs display reduced surface defect states, higher photoluminescence quantum yields together with improved stability. Subsequently, both CsPbI₃ and F-CsPbI₃ PQDs are utilized as interface engineering layer in PSCs, delivering the best efficiency values of 21.99% and 23.42%, respectively, which is significantly enhanced compared to the control device (20.37%). More importantly, benefiting from its more hydrophobic properties, the F-CsPbI₃ PQD treated device exhibits excellent ambient storage stability (25 °C, relative humidity: 35–45%), retaining over 80% of its initial efficiency after 1500 h aging.