RSC Advances
·
2021
·Vol. 11
·期 30
·18326-18332
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IF 3.361
Ying Lu,Zhihang Zhao,Xianpeng Fan,Xinyu Cao,Mingtan Hai,Zhou Yang,Kun Zheng,Jiaxin Lu,Jingnan Zhang,Yongmei Ma,Rongben Zhang,Shibi Fang
To obtain a rapid processible LED encapsulant that leads to high and stable light extraction efficiency (LEE), UV curable ZrO2/phenyl-siloxane nano-composite (ZSC) double-layer encapsulants were prepared and optimized. The highly crystalline ZrO2 nanoparticles with a diameter of ∼14 nm were synthesized through a modified hydrothermal method at mild conditions, and a UV curable methacryl-diphenyl-polysiloxane (MDPS) with a refractive index (RI) of 1.54 (at 633 nm) was synthesized from self-condensation of diphenylsilanediol and an end-capping reaction. High refractive indexes (RIs) from 1.54–1.61 have been obtained for ZSC composites by adding 0–20 wt% ZrO2. Before and after sulfur vapor erosion, the double-layer encapsulated sample (M-10/M) showed 11.2% and 64.8% higher LEE respectively than that of Dow Corning OE-7662. Meanwhile, the variation of LED light color temperature (Tc) was less than 1%. The effect of the ZrO2 nanoparticle content on LEE of double-layer and single-layer encapsulation were compared and discussed based on Fresnel loss and Rayleigh scattering theories. The double-layered UV curing processing took only 1/6 of the time needed for common thermal curing.
研究领域:
材料科学
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光学工程
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DOI
PubMed
高影响因子
ACS Nano
·
2020
·
IF 14.588
Jia-Sheng Li,Yong Tang,Zong-Tao Li,Jie-Xin Li,Xin-Rui Ding,Bin-Hai Yu,Shu-Dong Yu,Jian-Zhen Ou,Hao-Chung Kuo
In this study, we analyze the influence of the pore structure of an SBA-15 particle on the light emission from its inner adsorbed quantum dots (QDs) and outer light-emitting diode (LED) chips. It is found that the particle features of a high refractive index, comparable feature size of pore structure, and lower amount of QD adsorption help with QD light extraction, demonstrating a mechanism to suppress QD light propagating through pores and thus reducing the reabsorption loss. We consequently developed highly efficient QD white LEDs with wet-mixing QD/SBA-15 nanocomposite particles (NPs) by further optimizing the packaging methods and the introduced NP mass ratio. The LEDs demonstrated a record luminous efficacy (the ratio of luminous flux to electrical power) of 206.8 (entrusted test efficiency of 205.8 lm W–1 certificated by China National Accreditation Service) and 137.6 lm W–1 at 20 mA for white LEDs integrating only green QDs and green–red QD color convertors, respectively, with improved operating stability. These results are comparable to conventional phosphor-based white LEDs, which can be a starting point for white LEDs only using QDs as convertors toward commercialization in the near future.
研究领域:
材料科学
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光学工程
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DOI
PubMed
高影响因子
OPTICAL MATERIALS
·
2024
·
IF 3.8
Yanbin Wang,Ziqiu Cheng,Junhao Ye,Haohong Chen,Chen Hu,Zhenzhen Zhou,Yuyang Chen,Yudie Yang,Denis Yu Kosyanov,Jiang Li
Based on the “effective ionic radius match effect” and the “charge balance substitution rule of ions”, mixed Ba 2+ , Al 3+ , Lu 3+ , and Ce 3+ ions can be effectively regulated to a BaAl 2 O 4 -LuAG:Ce biphasic structure. The contribution of BaAl 2 O 4 like as scattering centers can reduce overall reflection losses and enhance the light extraction efficiency of these composite phosphor ceramics (CPCs). In this work, a series of x wt.% BaAl 2 O 4 -LuAG:Ce ( x = 0, 3, 5, 10, 15) CPCs were fabricated by vacuum sintering using co-precipitated composite powders. Homogenization at the atomic level of mixed Ba 3+ , Al 3+ , Lu 3+ , and Ce 3+ ions in multiphase powders provides uniform distribution of BaAl 2 O 4 and LuAG:Ce constituent phases in composite ceramics. The introduction of BaAl 2 O 4 has an additive effect, which also consists in uniform aggregation of pores near their grains during sintering. It allows to adjust the size and amount of microstructural defects by varying the secondary phase content. Under the excitation of 10.8 W 450 nm LDs in a reflection mode, 3 wt% BaAl 2 O 4 -based CPCs show the optimum luminous flux of 2244 lm and a luminous efficiency of 208 lm·W −1 . The obtained CPCs show a high application potential in solid-state laser lighting.
研究领域:
材料科学
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光学工程
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DOI
高影响因子
Journal of Materials Chemistry C
·
2022
·Vol. 10
·期 42
·16147-16156
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IF 8.067
Hailiang Fang,Beiying Zhou,Jiancheng Wang,Xiaobo Hu,Zesheng Pan,Shengjie Fan,Ping Huang,Shijia Gu,Lianjun Wang,Wan Jiang
Due to high thermal conductivity and excellent laser irradiation resistance, composite phosphor ceramics (CPCs) have been widely acknowledged as ideal color converters in laser lighting. However, achieving high-efficiency laser lighting is significantly limited by the inefficient utilization of pumping light. Microstructural tailoring is recognized as a promising strategy to improve the light extraction efficiency, while it is restricted by the harsh preparation conditions. Herein, we propose a novel Y2O3-YAG:Ce CPC controllably prepared from mesoporous Y2O3 powders and YAG:Ce phosphors using spark plasma sintering at a low temperature of 1160 °C. Attributed to the introduced Rayleigh scattering centers tailored by fine ceramic grains and well-matching of refractive indexes between the phosphor and the matrix, the Y2O3-YAG:Ce CPC exhibits an ultra-high relative internal quantum efficiency of 107% compared to that of the YAG:Ce phosphor. Impressively, when irradiated under a 450 nm laser diode, the as-prepared CPC produces white light with a high luminous efficiency of 178.42 l m W−1 and a low correlated color temperature of 4638 K, reflecting the enhanced light conversion efficiency. Furthermore, the CPC presents a remarkable improvement in thermal stability (only 6% luminescence loss at 200 °C) and is able to withstand a high laser flux density up to 6.16 W mm−2. These results demonstrate that the optimized Y2O3-YAG:Ce CPCs with designed microstructures are well suited for solid-state laser lighting with high power and brightness.
研究领域:
材料科学
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光学工程
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DOI
高影响因子
Nano Energy
·
2022
·
IF 19.069
Zhihai Wu,Yichen Zhang,Bintao Du,Keyang Yang,Jun Wu,Tianyi Dai,Chengkun Dong,Jun Xia,Anlang Wu,Zhenfu Zhao
Perovskite nanocrystals (PNCs) are promising to replace the traditional phosphor color conversion layers in backlit displays due to their excellent optical properties , which can enhance the color gamut and saturation of displays. However, poor stability and low luminescence efficiency hinder the development of perovskite-based devices. Here, inspired by the Yunnan cicada wing, a low-cost, easy-to-fabricate, and large-area (> 78 cm 2 ) all-dielectric metasurface based on the Purcell effect is developed to tune and improve the light extraction efficiency of PNCs. All-dielectric metasurfaces composed of weakly disordered TiO 2 /PS spheres are embedded in the PNCs/PVDF ( Poly (vinylidene fluoride)) films prepared by in-situ fabrication strategy, resulting in 3.19-fold photoluminescence (PL) maximum enhancement of these composite films . The stability of PNCs is also markedly improved after PVDF encapsulation. As an application demo, these all-dielectric metasurface-modulated perovskite composite films are applied in LCD backlit, with the color gamut of 157% of commercial LCD and 107% of NTSC, showing tremendous potential in high-end lighting and display. Furthermore, combined with the scalability of large-area fabrication, cost-effective weakly disordered metasurfaces are a potential method to bridge the gap between high-efficient laboratory demonstrations and commercialization in the field of display.
研究领域:
材料科学
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光电技术
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高影响因子
Nano Research
·
2023
·Vol. 16
·期 7
·10156-10163
·
IF 9.9
Li Haotao,Tian Fengshou,Chen Shuming
The importance of optical resonance in enhancing light outcoupling efficiency (OCE) is frequently overlooked in conventional bottom-emitting quantum-dot light-emitting diodes (QLEDs) due to their weak microcavity effect. Herein, we show that by synergistically optimizing the optical and the electrical performances, QLEDs with efficiency approaching the theoretical limit can be realized. By introducing a high refractive index indium zinc oxide (IZO) electrode and optimizing its thickness, the light OCE is significantly improved and consequently the red QLEDs exhibit an external quantum efficiency (EQE) of 33.2%, which is 1.4-fold higher than that of the reference devices with conventional indium tin oxide (ITO) electrodes. Moreover, with a high refractive index plastic substrate and a microlens array, the EQE can further be improved to a record value of 37.5%. Similar results are obtained in green and blue devices, which show an EQE of 18.8% and 14.4%, respectively. We also predict that the theoretical EQE limit of red, green, and blue QLEDs can reach 35.4%–36.5%, 24.8%–34.0%, and 25.1%–35.8%, respectively, without using any light outcoupling structures. The proposed synergistic optimization strategy enables the efficiencies of red, green, and blue QLEDs to approach their theoretical limits.
研究领域:
光电子学
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纳米技术
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材料科学
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固体物理
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高影响因子
ADVANCED MATERIALS
·
2025
·
IF 26.8
Dawei Yang,Yiduo Wang,Jing Xie,Daocheng Pan,Bingsuo Zou,Heng Zhang
Despite excellent efficiency and stability achieved in regular single-unit quantum dot light-emitting diodes (QLEDs), regular tandem QLEDs still suffer from limited device performance, lagging far behind the inverted tandem QLEDs. Here, novel regular tandem QLEDs are demonstrated with an ultrathin (≈4 nm) indium tin oxide (ITO) charge generation layer (CGL). Through systematic optimization of charge injection balance and light out-coupling efficiency, the resulting tandem QLEDs can exhibit a record-breaking EQE of 51.2%, an exceptional T 95 lifetime of ≈31383 h (at 1000 cd m −2 ), and an ultralow turn-on voltage of 2.8 V, which represent the highest performance metrics reported to date for regular tandem QLEDs. Thanks to the fast response of this tandem device (≈4.8 µs), the first-ever fabricated 8 × 8 passive-matrix displays can present flicker-free images with either fixed color or dynamically transitioning colors at a stable brightness, demonstrating that the achievable color display capability and driving scheme of QLED displays can be expanded by using the tandem architecture. It is believed the results will significantly promote the development of regular tandem QLEDs, which will lead to unprecedented improvements in device efficiency and stability, accelerating their application in next-generation displays and lighting.
研究领域:
光电子学
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纳米技术
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材料科学
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显示技术
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固体物理学
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DOI
PubMed
高影响因子
ACS Materials Letters
·
2021
·
IF 8.312
Jiaxue Zhang,Qianying Lu,Yanyan Li,Tingyu Li,Ming-Hui Lu,Yan-Feng Chen,Desheng Kong
Stretchable optoelectronics represent an emerging technology featuring soft mechanical properties. The advancements in this active area rely on the development of compliant electronic materials. Currently, the deformable forms of light-emitting devices often exhibit double-side emissions due to the lack of stretchable reflective electrodes. This study reports a facile procedure to deposit smooth and uniform liquid metal films over large-area elastomeric substrates as stretchable reflective electrodes. The as-prepared electrodes exhibit low sheet resistance (0.15 Ω sq–1), high optical reflectance (95% at 550 nm), and ultrahigh deformability (500% strain). The electrode shows sufficient durability to survive repetitive tensile deformations. Successful implementation of a liquid metal electrode in a stretchable light-emitting device achieves single-side emission with enhanced light extraction. The stretchable reflective electrode reported here represents a key building component to enable a broad range of applications such as deformable lighting, wearable displays, and soft robotics.
研究领域:
材料科学
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光电子学
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可穿戴技术
·
软体机器人
✓ 已验证
DOI
高影响因子
Advanced Materials Interfaces
·
2021
·Vol. 9
·期 1
·2101485
·
IF 6.147
Binhai Yu,Zijian Huang,Dong Fang,Shudong Yu,Ting Fu,Yong Tang,Zongtao Li
Inspired by the Cyphochilus scale with extreme whiteness, fluoropolymer is used as the matrix to prepare highly scattering porous polymer films through polymerization-induced phase separation (PIPS) method. The mixture used for the PIPS technique contains a fluoride monomer, a UV photoinitiator, and porogens (cyclohexanol and perfluorooctanol). By carefully tuning the mixture parameters (cyclohexanol–perfluorooctanol and monomer–porogen weight ratios), the porous morphology can be well tailored, which induces different scattering performances. With an optimized formulation (50 wt% monomer, 25 wt% cyclohexanol, and 25 wt% perfluorooctanol), the porous film with a thickness of 55 µm can achieve an average total reflectance of ≈90%, featuring a measured transport mean free path of 1.3–1.7 µm (comparable to the 1.5 µm of the benchmark Cyphochilus scale). Further, the porous films are applied to the light-emitting diode (LED) device and it is demonstrated that they can effectively improve the light extraction efficiency of the LED and thus enhance the luminous performance. Due to the simplicity, cost-effectiveness, and scalability of the PIPS method, the as-developed porous fluoropolymer films with such excellent scattering ability can find many potential applications not only in the field of optoelectronics, but also in various complex scenarios, such as daytime passive radiative cooling.
研究领域:
材料科学
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光学
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工程学
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纳米技术
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DOI
高影响因子
Advanced Optical Materials
·
2022
·Vol. 10
·期 12
·2102742
·
IF 10.05
Wei Chen,Chuan Xu,Lingqing Kong,Xiang-Yang Liu,Xingye Zhang,Naibo Lin,Xinhua Ouyang
It is an essential issue for the efficiency of flexible organic light-emitting diodes (OLEDs) to be improved in display and lighting applications. Herein, the use of silk fibroin (SF) as a flexible OLED substrate with enhanced light extraction efficiency (LEE) is reported. Regenerated SF is prepared via a casting method and then coated with conductive indium tin oxide (ITO) via magnetron sputtering. SF-based flexible OLED outperforms its reference device in terms of turn-on voltage, peak brightness, and LEE, where glass and polyethylene terephthalate are used as rigid and flexible substrates, respectively. The improved device performance can be ascribed to the low refractive index of SF and its lower surface roughness and more matched energy levels compared to those of other substrates, resulting in a high LEE. Notably, a molecular dipole layer can be formed between the interface of ITO and SF. The dipole moment pointing to the ITO surface effectively changes the ITO work function and reduces the potential barrier height for hole transfer. The work provides new ideas for constructing high-performance OLEDs on biomass-based substrates with excellent flexibilities and high LEEs.
研究领域:
材料科学
·
光电技术
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显示技术
·
柔性电子
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DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2022
·
IF 7.968
Yifeng Zhang,Shuo Zhang,Haorong Sun,Zhe Wang,Feixue Gao,Jiawei Zhang,Zezheng Liu,Ming Fang,Xiaoli Tan,Xiangke Wang
Photocatalytic U(VI) extraction is considered as the most promising way to solve the current shortage of uranium resources and radioactive contamination. In this work, O-doped hexagonal-cubic CdS phase heterojunction was constructed by a simple thermal treatment and was successfully used for the photoextraction of U(VI) from water bodies. The samples with different heat treatment temperatures have different phase ratios and oxygen doping amounts. The experimental results show that the CdS heat treated at 350 °C (CdS-350) has the best photocatalytic activity, which can extract 80% of uranium within 120 min (m/v CdS-350 = 0.4 mg/g, C U(VI) = 50 ppm). More interestingly, a systematic mechanistic investigation shows that the extraction process is divided into two steps: i.e., photoelectrons and • O 2 − reducing U(VI) to U(IV) first, followed by photoholes and • OH oxidizing U(IV) to insoluble U(VI) (UO 2 (OH) 2 ). The second step of oxidation allows CdS-350 to avoid photocorrosion, resulting in an excellent recycling performance of only 8% decrease in performance after four cycles.
研究领域:
环境科学
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材料科学
·
化学
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DOI
高影响因子
危险品化学品经营许可证（带存储）