ABSTRACT A high‐quality quantum dots (QDs) layer is crucial for the commercialization of quantum dot light‐emitting diode (QLED) devices. However, current fabrication techniques cannot simultaneously achieve monolayer coverage, ordered arrangement, and large‐area scalability. Herein, we develop a novel strategy of continuous stepwise self‐assembly for QDs monolayer integrated the air‐liquid interfacial assembly technology with continuous line‐ink‐supply and Langmuir‐Schaefer (LS) technology, which the QDs can be finely to assemble into large area ordered and dense QDs monolayer film at the trailing edge of the flow. The ordered QD monolayers can be repeatedly transferred and stacked to accurately control the thickness of the luminescent layer in QLED devices. Green QLED based on this monolayer film reaches a high EQE of 23.85%. Furthermore, the optimized trilayer device exhibits negligible efficiency roll‐off, retaining an EQE above 18% and a luminous efficacy of 60 lm W −1 at a luminance of 200 000 cd m −2 . This methodology also shows preliminary scalability potential. We achieved a trial fabrication of large‐area QD films of 210 cm 2 and further constructed corresponding QLED devices with an emission area of 1.5 cm × 1.5 cm as an initial exploration.

The red QLEDs employing a pH-neutral PEDOT:PMA hole injection layer synthesized using phosphomolybdic acid exhibit an impressive EQE of up to 32.24% along with remarkable operational stability.

The degradation of the underlying perovskite quantum dot (PQD) layers by the ZnMgO ink hinders the performance of all-solution-processed perovskite quantum dot light-emitting diodes (P-QLEDs). Herein, a novel dual-sided interface optimization is proposed for the fabrication of P-QLEDs: (i) cross-locking PQD surface ions with a robust zwitterionic ligand to boost their chemical and solvent tolerance; (ii) improving ink orthogonality via optimizing the solvent of ZnMgO to acetonitrile and eliminating residual hydroxyl groups from the ZnMgO surface. As a result, the ZnMgO is deposited on the PQD films without causing serious degradation, leading to improved carrier injection and radiative recombination. The optimized P-QLEDs achieve a maximum luminance of 134 920 cd m-2 and a peak external quantum efficiency (EQE) of 8.3%, ranking among the state-of-the-art all-solution-processed green-emitting devices.

The Zinc-Magnesium oxide (ZnMgO, ZMO) nanoparticles (NPs) are well-documented as electron transport layer (ETL) in quantum dot light-emitting diodes (QLEDs). However, ZnO/ZMO nanoparticles prepared via low-temperature sol-gel methods with small grain size and abundant surface defects always suffer from structural and electrical drift, causing lifespan reduction and performance fluctuations of devices. Herein, the benzyl phosphate (BPA) and its derivatives are introduced onto the surface of ZMO NPs as armor layer to stabilize and regulate their properties as ETLs. The prepared ZMO capped with BPA NPs have fine structural and electrical properties stability, which have simultaneously achieves effective defect passivation, enhances nanoparticle dispersibility and stability, and precisely tunes energy levels to balance charge injection. By benefiting from the robust ZMO ETLs, the overall performance of the QLED devices has been greatly boosted. The resulting external quantum efficiency (EQE) of green QLEDs is increased from 20.8% to 29.9%, showing the best performance among currently reported ZMO-based green QLEDs, and over 3.3-fold improvement in T95 operation lifetime at 1000 cd m- 2. The relevant physical mechanism has also been investigated. Current work will inspire the exploration of ZMO decorating engineering to construct solution-processed QLEDs device with higher performance.

The poor efficiency and stability of blue Quantum Dot Light-Emitting diodes (QLED) hinders the practical applications of QLEDs full-color displays. Excessive electron injection, insufficient hole injection, and abundant defects on the surface of quantum dots (QD) are the main issues limiting the performance of blue devices. Herein, an in situ treatment with bipolar small molecule polydentate ligand-guanidine chloride (GACl) is proposed to simultaneously suppress excessive electron injection, patch surface defects of QDs and enhance hole injection. GACl-treated blue QLEDs exhibited a remarkable increase in maximal external quantum Efficiency (EQE) from 16.3% to a record 23.5%, accompanied by maximal luminance (36810 cd m-2), excellent maximal current efficiency (17.5 cd A-1), and enhanced device stability. Combining C-V and J-V characteristics, a concise physical model of hole injection is also established: Below 3 V, hole injection is controlled by the interfacial barrier, primarily through tunneling and thermionic injection; Above 3 V, the interfacial barrier is eliminated, and hole injection efficiency is governed by transport within the QD layer. This study showed a clear physical model for understanding the hole injection mechanism in QLEDs, offering valuable design strategies for improving the performance of blue-QLEDs.

The poor efficiency and stability of blue quantum dot light-emitting diodes (QLED) hinder its practical applications in full-color displays. Insufficient hole injection and excessive surface defects in quantum dots (QD) layer remain the primary challenges limiting the performance of blue devices. Herein, a dual interface modification strategy is proposed to enhance the performance of blue QLED by synergistically regulating both the electronic transport layer (ETL)/QD and hole transport layer (HTL) HTL/QD interfaces. At the HTL/QD interface, the introduction of guanidine sulfamate (GAS) ligands passivates QD surface defects while reducing the hole injection barrier, thereby improving hole injection efficiency in the low-bias region. Meanwhile, at the QD/ETL interface, Guanidine chloride (GACl) ligands are incorporated to passivate interfacial defects, suppress leakage current, and suppress excessive electron injection, thus enhancing hole transport efficiency within the QDs layer. The synergistic effect of bilateral GA-based ligands can simultaneously enhance the hole injection efficiency based upon improving the hole transport efficiency, significantly increasing the radiative recombination ratio during device operation. As a result, the dual-ligand modified blue QLEDs achieve a remarkable improvement in external quantum efficiency (EQE) from 16.6% to 24.3%, and a sevenfold enhancement in operational lifetime.

Despite the rapid advances of red and green perovskite light-emitting diodes（Pe LEDs）, achieving high brightness with high external quantum efficiency（EQE） remains a challenge for the pure-blue Pe LEDs,which greatly hinders their practical applications, such as white-light illumination and in optical communication as a high-speed and low-loss light source. Herein, we report a high-performance pure-blue Pe LED based on mixed-halide quasi-2D perovskites incorporated with a zwitterionic molecule of 3-（benzyldimethylammonio）propanesulfonate（3-BAS）. Experimental and density functional theory analysis reveals that 3-BAS can simultaneously eliminate non-radiative recombination loss, suppress halide migration, and regulate phase distribution for smoothing energy transfer in the mixed-halide quasi-2D perovskites, leading to the final perovskites with high photoluminescence quantum yield and robust spectrum stability. Thus, the highperformance pure-blue Pe LED with a recorded brightness with 1806 cd m -2 and a relative higher EQE of 9.25% is achieved, which is successfully demonstrated in a visible light communication system for voice signal transmission. We pave the way for achieving highly efficient pure-blue Pe LEDs with great application potential in future optical communication networks.

Developing an insoluble cross-linkable hole transport layer (HTL) plays an important role for solution-processed quantum dots light-emitting diodes (QLEDs) to fabricate a multilayer device with separated quantum dots layers and HTLs. In this work, a facile photothermal synergic cross-linking strategy is simultaneous annealing and UV irradiation to form the high-quality cross-linked film as the HTL without any photoinitiator, which efficiently reduces the cross-linking temperature to the low temperature of 130 °C and enhances the hole mobility of the 3-vinyl-9-{4-[4-(3-vinylcarbazol-9-yl)phenyl]phenyl}carbazole (CBP-V) thin films. The obtained high-quality cross-linked CBP-V films exhibited smooth morphology, excellent solvent resistance, and high mobility. Moreover, the high-performance red, green, and blue (RGB) QLEDs are successfully fabricated by using the photothermal synergic cross-linked HTLs, which achieved the maximum external quantum efficiency of 25.69, 24.42, and 16.51%, respectively. This work presents a strategy of using the photothermal synergic cross-linked HTLs for fabrication of high-performance QLEDs and advancing their related device applications.

Breaking the theoretical limits of external quantum efficiency (EQE) and obtaining quantum dot light-emitting diodes (QLEDs) with high brightness, high efficiency, and low operating voltage is the basis of commercial applications in display and illumination. Devices with an EQE of over 20% can be realized by carrier equilibrium injection and light out-coupling enhancement. However, it is difficult to synergistically enhance the performance of QLEDs by combining the light out-coupling and the hole enhancement injection. In this paper, the injection enhancement of holes and the light out-coupling are realized simultaneously only by nano-imprint lithography (NIL). The pi & horbar;pi bonds of the PEDOT: PSS film treated by NIL demonstrate a molecular orientation perpendicular to the substrate, which improves the injection of the hole. The PEDOT: PSS patterned by NIL further presents improved light out-coupling. Consequently, the EQE of red-QLED is 30.42% with a synergistic enhancement factor of 61%, accompanying the maximum brightness increased by 8% to 125 200 cd m(-2) at 4.6 V (Vturn-on, 1.74 V). The EQE and brightness of green-QLED increased by 38.9% and 34.3% to 24.16% and 279 700 cd m(-2), respectively. Therefore, NIL will provide new insights into synergistically enhancing light out-coupling and internal quantum efficiency to break through the performance of electroluminescence (EL).

Quantum-dot light-emitting diodes (QLEDs), a kind of promising optoelectronic device, demonstrate potential superiority in next-generation display technology. Thermal cross-linked hole transport materials (HTMs) have been employed in solution-processed QLEDs due to their excellent thermal stability and solvent resistance, whereas the unbalanced charge injection and high cross-linking temperature of cross-linked HTMs can inhibit the efficiency of QLEDs and limit their application. Herein, a low-temperature cross-linked HTM of 4,4 '-bis(3-(((4-vinylbenzyl)oxy)methyl)-9H-carbazol-9-yl)-1,1 '-biphenyl (DV-CBP) with a flexible styrene side chain is introduced, which reduces the cross-linking temperature to 150 degrees C and enhances the hole mobility up to 1.01 x 10(-3) cm(2) V-1 s(-1). More importantly, the maximum external quantum efficiency of 21.35% is successfully obtained on the basis of the DV-CBP as a cross-linked hole transport layer (HTL) for blue QLEDs. The low-temperature cross-linked high-mobility HTL using flexible side chains could be an excellent alternative for future HTL development.

Metal halide perovskite light-emitting diodes (PeLEDs) are ideal for high-resolution displays due to their tunable emission, narrow spectra, and low-cost processing. Colloidal FAPbBr3 perovskite quantum dots (PeQDs) enhance radiative recombination, making them efficient for pure-green PeLEDs. However, their low stability and surface defects limit their practical application. Here, we address these challenges by proposing an in situ surface repair strategy using benzhydroxamic acid (BHA) as a modifier. We demonstrated that BHA can coordinate with Pb2+ ions and form hydrogen bonds with FA+ and halide ions, effectively reducing nonradiative recombination and maintaining the integrity of the PeQDs. High-quality FAPbBr3 PeQDs with a photoluminescence quantum yield (PLQY) of up to 92.5% were achieved, leading to pure-green PeLEDs with an external quantum efficiency (EQE) of 24.8% and a maximum luminance of 40,231 cd m-2, providing a feasible and promising perspective for advanced solid-state lighting and displays.

Zinc oxide nanoparticles (ZnO NPs) have been actively pursued as the most effective electron transport layer for quantum-dot light-emitting diodes (QLEDs) in light of their unique optical and electronic properties and low-temperature processing. However, the high electron mobility and smooth energy level alignment at QDs/ZnO/cathode interfaces cause electron over-injection, which aggravates non-radiative Auger recombination. Meanwhile, the abundant defects hydroxyl group (-OH) and oxygen vacancies (O-V) in ZnO NPs act as trap states inducing exciton quenching, which synergistically reduces the effective radiation recombination for degrading the device performance. Here, we develop a bifunctional surface engineering strategy to synthesize ZnO NPs with low defect density and high environmental stability by using ethylenediaminetetraacetic acid dipotassium salt (EDTAK) as an additive. The additive effectively passivates surface defects in ZnO NPs and induces chemical doping simultaneously. Bifunctional engineering alleviates electron excess injection by elevating the conduction band level of ZnO to promote charge balance. As a result, state-of-the-art blue QLEDs with an EQE of 16.31% and a T-50@100 cd m(-2) of 1685 h are achieved, providing a novel and effective strategy to fabricate blue QLEDs with high efficiency and a long operating lifetime.

Quantum dot light-emitting diodes (QLEDs), based on the solution-processable colloidal quantum dots (QDs), are the high potential candidate for next generation display and lighting due to their high color purity, wide color gamut, low power consumption, and wide angle of view. Efforts have been made to improve the performance of the devices in order to achieve the goals of practical applications. This review focuses on the research progress in the materials and device physics of QLEDs, with the aims to accelerate the process of overcoming the obstacles to commercialization. Herein, the unique optical properties of QDs and the evolution of device structures are first reviewed. Then carrier dynamics, which has a decisive impact on device performance, is discussed in detail. In addition, the main obstacle to commercialization is emphasized as device stability, including operational stability, shelf stability, and efficiency roll-off. Finally, unresolved issues in device physics are discussed, along with suggestions for future research directions. This review is expected to encourage further research in device physics and promote the development of QLEDs in the field of display and solid-state lighting.

控制性详细规划课程教学的难点是如何帮助学生理解控制指标和空间形态之间的关系.文章介绍结合教学实践,尝试在课程中设置"控制指标空间形态模拟"这一教学模块,使学生通过现场踏勘、制作模型、计算机模拟等过程,增强对控制指标和空间形态之间的认知.

The brightness of white quantum dot light-emitting diodes (W-QLEDs) is one of the most important indicators for their commercialization. However, the brightness of W-QLEDs is severely limited by the light trapped in the substrate mode. In this work, a prototype W-QLED with the original brightness of 88 181 cd m(-2) is fabricated by using a mixture of red-, green-, and blue-emitting quantum dots as a light emitting layer. Then, a tailored wrinkle pattern is attached on the bottom of the glass substrate of W-QLEDs for the further light extraction. Different from the widely used external periodic patterns, the wrinkle patterns with richer Fourier spectra can outcouple the tricolor light trapped in the substrate mode simultaneously. In this case, the brightness of W-QLEDs has a 54.4% enhancement to an ultra-high value 136 207 cd m(-2), and realizes the quasi-Lambertian emission. The external quantum efficiency is improved from 9.68% to 13.41%. Meanwhile, correlated color-temperature can cover a wider span transforming from pure white light (5115 K) to cold white light (6912 K). This work proposes a unique and efficient approach for the light extraction and color control of W-QLEDs for their real application.

Highly efficient blue quantum-dot light-emitting diodes (QLEDs) are still challenging to use in displays and solid-state lighting. Enhancing light outcoupling is one of the most effective methods to improve the performance of blue QLEDs. Here, a strategy for a spectrally independent boost in light outcoupling of blue QLEDs is demonstrated by quasi-periodic wrinkles, which are successfully used as a diffraction grating for extracting trapped light at the substrate/air interface. The quasi-periodic wrinkles can be adjusted from nano-scale to micron-scale under the condition of a constant aspect ratio, and the optimized wrinkle device shows a maximum luminance of 11 769 cd m-2 and a peak EQE of 15.41%. The enhancement of EQE is 49.5% higher compared to that of the reference device. Furthermore, simulation and calculation also indicate that external micron-scattering wrinkle patterns are an attractive option for boosting the performances of blue QLEDs.

Correction for 'High performance blue quantum light-emitting diodes by attaching diffraction wrinkle patterns' by Hui Qi et al., Nanoscale, 2021, DOI: 10.1039/D1NR00082A.

The latest progress of blue light-emitting diodes based on II–VI semiconductor QDs was reviewed, covering the synthesis of blue QDs, device structures, carrier transport materials, interface regulation, and light outcoupling technology.

In this article, two Keggin-type polyoxometalates [Co(L)2]3[PMo12O40] (1) and [Co(L)2]3[PW12O40] (2) (HL = 2-acetylpyrazine thiosemicarbazone) were prepared and fully characterized. The compounds are stable in aqueous solution with different pH values and show superior antibacterial activity against Escherichia coli (E. coli: minimal inhibitory concentration (MIC) = 0.00375, 0.12 μg/mL), Agrobacterium tumefaciens (A. tumefaciens: MIC = 0.06, 0.12 μg/mL), Bacillus subtilis (B. subtilis: MIC = 0.015, 0.06 μg/mL) and especially for Staphylococcus aureus (S. aureus: MIC = 0.00048, 0.015 μg/mL) for 1 and 2, respectively. The time kill studies showed the entire killing of specific bacteria during 4 to 8 h. In addition, the possible antibacterial mechanism of compound 1 was explored systematically. The experimental results proved that cell wall/membrane damage, leakage of protein, inhibition of respiratory chain dehydrogenases activity, enhancement of intracellular reactive oxygen species (ROS) and depletion of glutathione (GSH) were the potential causes of bacteria death.

In this article, a new compound H-2[{Cu(HL)(H2O)}(2)(P2Mo5O23)]center dot 5H(2)O (1) (HL= 2-acetylpyrazine thiosemicarbazone) has been synthesized and structurally characterized by single-crystal X-ray diffraction of and other detection techniques. Interestingly, the structure of 1 is different from many reported copper-based complexes, in which the [P2Mo5O23](6-), two Cu2+ ions and two HL were directly connected by covalent bands. Biological studies demonstrated that 1 indicated moderate antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and a better cytotoxicity against human hepatic cancer line (SMMC-7721) than Mitoxantrone (Mito), the current clinical anticancer drug. Besides, the antibacterial mechanisms of 1 have been studied by the membrane integrity disruption, the destructive reactive oxygen species generation (ROS), the glutathione (GSH) depletion and the depressed enzymatic activity of respiratory chain dehydrogenases (RCD). These results revealed that the combination of HL, Cu2+, [P2Mo5O23](6-) shows a higher antibacterial and cytotoxic activity.