查找使用阿拉丁产品的科研文献

Unveiling self-trapped exciton emission in lanthanide-doped Cs2NaInCl6 double perovskites for efficient white LEDs

Hu Bao-Ye,Zhang Wei-Qiang,Zhao Guang-Jiu,Rosei Federico,Zhang Xian-Xi,Zhao Jin-Sheng,Xu Long-Jun,Chu Ya

Lead-free halide double perovskite-based white light-emitting diodes (WLEDs) have recently emerged as promising candidates for advanced lighting technologies. However, their inherent characteristics, such as indirect bandgaps and forbidden electronic transitions, significantly limit photoluminescence (PL) efficiency, posing critical challenges to their widespread application. Herein, we selected highly efficient blue-emitting Cs 2 NaInCl 6 :Bi 3+ nanocrystals (NCs) as a matrix, into which lanthanide ions (Ln 3+ ) were incorporated by ion doping, yielding a series of Ln 3+ -doped perovskite NCs, Cs 2 NaInCl 6 :Bi 3+ ,Ln 3+ (Ln 3+  = Eu 3+ , Tb 3+ and Dy 3+ ), with an impressive photoluminescence quantum yield (PLQY) of 85.1%. Doping with Ln 3+ effectively regulates the optical bandgap and PL efficiency of these materials. Femtosecond transient absorption (fs-TA) spectroscopy reveals changes in self-trapped exciton (STE) dynamics and reduced deep trap-related states upon Ln 3+ doping, indicating effective modulation of self-trapping and defect passivation. The lead-free halide double perovskite-based WLED devices were demonstrated by coating the highly fluorescent green-emissive Cs 2 NaInCl 6 :Bi 3+ ,Tb 3+ NCs with red-emitting (Sr, Ca)AlSiN 3 :Eu phosphor on a commercial ultraviolet (UV) chip, achieving a color-rendering index (CRI) of 87.5 and a correlated color temperature (CCT) of 5723 K. This study is laying a theoretical foundation for the regulation of the optical properties of lead-free halide double-perovskite NCs and defining an ideal model for the development of efficient WLEDs. Graphical We developed a family of Ln 3+ -Bi 3+ co-doped NCs, Cs 2 NaInCl 6 :Bi 3+ ,Ln 3+ (Ln 3+  = Eu 3+ , Tb 3+ , Dy 3+ ), with multicolor luminescence and excellent stability. The luminescence mechanism revealed energy transfer from Bi 3+ to Ln 3+ and achieved efficient self-trapping excitation emission of these materials. WLED device was fabricated using green emissive Cs 2 NaInCl 6 :Bi 3+ ,Tb 3+ NCs (PLQY = 85.1%) with excellent optical stability.

Improving the Efficiency and Stability of Green-Light Perovskite CsPbBr3 LEDs via Low-Temperature Annealing

Hui-Lian Zhou,Ya-Yang He,Yong Wang,Cheng-Yang Zhou,Hong-Wei Hu,Yun Zhang,Guang-Gui Cheng

All-inorganic lead bromide perovskite CsPbBr3 has garnered considerable attention due to its high thermal stability and rapid radiative recombination. Unfortunately, it is still a big challenge to further improve the efficiency and stability of the CsPbBr3 film via the solution processing technique. In this study, we report a method to enhance the CsPbBr3 film quality via annealing at a low temperature of 38 °C. The low-temperature annealing slows the phase transition, allowing for the orderly arrangement of crystal orientations and a surface with fewer defects. With this method, the fabricated CsPbBr3 PeLED exhibits great stability and bright luminescence, achieving an external quantum efficiency (EQE) of 8.21%. The PeLEDs fabricated at 38 °C demonstrated a low turn-on voltage of 1.5 V, with high current densities of 66.8 mA/cm2 at 2.0 V and 371 mA/cm2 at 3.0 V. These results provide valuable insights for the realization of high-efficiency and high-stability PeLEDs for lighting and display applications.

Microsized Red Luminescent MgAl2O4:Mn4+ Single-Crystal Phosphor Grown in Molten Salt for White LEDs

Zhaowu Wang,Haipeng Ji,Jian Xu,Xinghui Hou,Jumpei Ueda,Setsuhisa Tanabe,Shasha Yi,Ying Zhou,Deliang Chen

A single-crystalline defect-less phosphor is desired for efficient luminescence of the therein doped optical activators. In this paper, microsized MgAl2O4:Mn4+ single-crystal phosphors with bright red luminescence were grown in molten LiCl salt at 950 °C, for application in blue LED pumped white lighting. By comparing the phosphor formation from various Mg2+- and Al3+-bearing sources, both the template-formation and the dissolution-diffusion processes were evidenced to account for the formation of the microsized MgAl2O4:Mn4+ crystallites. Using nano γ-Al2O3 as the Al3+-bearing precursor, the uniform MgAl2O4:Mn4+ microcrystallites with a {111} planes-exposed tetragonal bipyramid morphology were obtained. The photoluminescence property was studied at various temperatures, and Mg ↔ Al anti-site disorder induced luminescence broadening was discussed. The Mn4+2Eg → 4A2g transition in MgAl2O4 shows a quite short luminescence wavelength peaking at 651 nm and ultrabroadband emission extending to 850 nm. The luminescence is relatively robust against thermal effect with relatively high thermal quenching temperature of 400 K and activation energy of 0.23 eV. Employing the red-emitting MgAl2O4:Mn4+ crystallites, blue LED pumped white lighting prototypes were fabricated which simulate the solar-like spectrum and show neutral to warm white.

A near UV-excited abnormal broad yellow emission phosphor Ba2CaB2Si4O14:Eu2+ for white-light LEDs

Pu Fan,Zefeng Xu,Qi Luo,Zongjie He,Yuhui Chen,Qiqi Miao,Cong Huang,Xiaoguang Liu,Ling Li

Phosphor-converted white LEDs are realized by combining blue InGaN chips with yellow and red emitting materials. Due to the lack of efficient red phosphor materials, we can design a broadband yellow phosphor material containing as many red components as possible. We found an abnormal broadband yellow-emitting Ba 2 CaB 2 Si 4 O 14 :Eu 2+ borosilicate phosphor inspired by natural minerals, which has been synthesized by traditional high temperature solid-state method. The structural information and photoluminescence characteristics of Ba 2 CaB 2 Si 4 O 14 :Eu 2+ were characterized in detail, and applied to the fabrication of white LED devices. Excited by near ultraviolet light at 365 nm, it displays a wide emission band from 400 to 800 nm centered on the 595 nm peak. White LED devices were fabricated by physically mixing the yellow phosphor Ba 2 CaB 2 Si 4 O 14 :Eu 2+ and synthesized blue phosphor BaMgAl 10 O 17 :Eu 2+ with 365 nm UV chip as excitation. The correlation color temperature (CCT) value and the chromaticity coordinates of the fabricated WLED devices were found to be 5522 K and (0.3293, 0.3036) respectively. In conclusion, Ba 2 CaB 2 Si 4 O 14 :Eu 2+ has great potential in the preparation of near UV excited white LEDs.

Inhibited thermal degradation of CsPbBr3 perovskite quantum dots by dual-Shell engineering towards stable LEDs

Mengxiang Nie,Xiaolin Zhu,Shengjie Jiang,Qingyu Xie,Long Luo,Liang Zhao,Min Zhou,Daofu Wu,Xiaosheng Tang,Jia Wang,Shengnan Tian,Yongfeng Liu

Halide perovskite quantum dots (PeQDs) have garnered significant attention for their exceptional optoelectronic properties, particularly in light-emitting diode (LED) applications. However, their susceptibility to thermal degradation at elevated temperatures (>100 °C) poses a critical barrier to commercialization. In this study, we address this challenge through a synergistic ZnF 2 post-treatment strategy applied to CsPbBr 3 PeQDs. Comprehensive experimental characterizations and density functional theory (DFT) calculations reveal that the ZnF 2 treatment induces the formation of a dual-shell structure: CsPbBr 3 : F inner shell and a zinc-rich outer shell chemically that bonds with Br and F ions from the CsPbBr 3 : F layer. The inner shell primarily suppresses thermal degradation, while both shells collaboratively mitigate surface defects. This dual-shell engineering endows the CsPbBr 3 PeQDs with remarkable thermal stability, maintaining their optical properties and crystallinity even after heating at 120 °C for 60 min, alongside achieving near-unity photoluminescent quantum yield. Furthermore, the dual-shell PeQDs exhibit a 24-fold enhancement in device lifespan in electroluminescent LEDs and superior operational stability in photoluminescent white LEDs. This work offers a simple yet highly effective approach to fabricating thermally stable PeQDs, paving the way for their practical application in next-generation optoelectronic devices.

Bulk Fabrication of Space-Confined CsPbI3 Nanocrystal Films Toward Efficient and Bright Deep-Red LEDs

Wenji Zhan,Haifei Wang,Jiahao Guo,Yugang Liang,Yanming Wang,Jixin Wu,Zhengzheng Dang,Ni Zhang,Jingjing Cao,Yingping Fan,Yu Zou,Bowei Li,Yao Wang,Yuetian Chen,Yanfeng Miao,Yixin Zhao

Deep-red light-emitting diodes (LEDs) with 690−710 nm emission show high significance in optical, agricultural, and biomedical applications. As primary candidates for deep-red emitters, all-inorganic CsPbI 3 films suffer from fused large grains with abundant trap states, leading to inferior performance of deep-red perovskite LEDs (PeLEDs). Here we report CsPbI 3 nanocrystal films with strong space confinement and notable performance at ∼700 nm of deep-red emission via bulk fabrication. The dual roles of diaza-18-crown-6 dihydriodide additive as crystallization regulator and Lewis base ligand trigger more nucleation sites, retarded grain growth and passivated trap states, ensuring the crystallization of high-quality space-confined CsPbI 3 nanocrystal films. This approach establishes a record-high external quantum efficiency (EQE) of 23.4% for deep-red PeLEDs, and achieves a maximum luminance of 10152 cd m −2 . Low roll-off is also demonstrated that EQE maintain over 20% under a high current density of 900 mA cm −2 , which is superior to state-of-the-art deep-red organic and quantum-dot LEDs. The T 50 operating lifetime is estimated to be 234 h at an initial radiance of 6.3 W sr −1 m −2 . This work provides an effectual strategy to accelerate radiative recombination and enhance the performance of CsPbI 3 -based deep-red PeLEDs.

Efficient Blue Perovskite LEDs via Bottom-Up Charge Manipulation for Solution-Processed Active-Matrix Displays

Yi Yu,Bing-Feng Wang,Yang Shen,Yu-Tong Wang,Yu-Hang Zhang,Ying-Ying Li,Zhen-Huang Su,Long-Xue Cao,Shi-Chi Feng,Yuan-Hang Wu,Xing-Yu Gao,Satoshi Kera,Nobuo Ueno,Jian-Xin Tang,Yan-Qing Li

Perovskite light-emitting diodes (PeLEDs) are emerging as strong candidates for next-generation displays due to their outstanding optoelectronic properties, solution processability, and cost-effectiveness. However, the development of highly efficient blue PeLEDs remains a significant challenge. Here, a bottom-up strategy is introduced for precise charge manipulation in blue perovskites to enhance radiative recombination efficiency. By employing 1,3-bis(N-carbazolyl)benzene as an inserted hole transport layer, improved hole injection efficiency is achieved while effectively suppressing reverse electron transport and exciton quenching. Additionally, a fluorinated ester additive is incorporated to control perovskite crystallization, facilitating the formation of well-aligned reduced-dimensional phases to reduce nonradiative recombination losses. The resulting blue PeLEDs exhibit a record-breaking external quantum efficiency of 25.87%, the highest reported for one-step-prepared blue perovskite films. Furthermore, integration with thin-film transistor circuits enables solution-processed active-matrix perovskite displays with sharp and uniform patterning. This work provides a comprehensive pathway for advancing blue PeLEDs toward high-performance display applications.

Near-Infrared Broadband ZnTa2O6:Cr3+ Phosphor for pc-LEDs and Its Application to Nondestructive Testing

Shaoxuan He,Panlai Li,Yinti Ren,Guohui Wei,Ye Wang,Yuanbo Yang,Rui Li,Jiehong Li,Yawei Shi,Xingqiang Shi,Zhijun Wang

Broadband near-infrared (NIR) phosphors are necessary materials for developing portable NIR light sources. Moreover, exploiting an NIR phosphor with a main peak located beyond a wavelength of 900 nm remains a challenge because this spectral range has great potential in biological nondestructive testing and solution testing. In this study, a range of Cr3+-doped ZnTa2O6 (ZTO) phosphors were completely synthesized by a solid-state method, which show broadband Cr3+ emission centered at 935 nm with a large full width at half maximum (FWHM) of 185 nm due to two distorted octahedral sites. A packaged phosphor-converted light-emitting diode (pc-LED) device is used to penetrate a 5-cm-thick chicken breast and identify diverse solutions based on differences in the measured transmission spectra. The results indicate broad application prospects in the field of biological tissue penetration and solution analysis.

Reduction of Die-Bonding Interface Thermal Resistance for High-Power LEDs Through Embedding Packaging Structure

Xiang Lei,Huai Zheng,Xing Guo,Zefeng Zhang,Jiading Wu,Chunlin Xu,Sheng Liu

Thermal management is a key issue for high-power light-emitting diodes (LEDs). In this study, a novel packaging structure was proposed to reduce the die-bonding interface thermal resistance and provided a new idea for LED heat-dissipation. The LED chip was embedded into a square groove at the lead-frame substrate. The gap between the edges of the LED chip and square groove was filled with boron nitride/silicone composite. So the heat generated from the chip could be dissipated from the side surfaces to the substrate. The experimental results show that the heat-dissipation ability of LEDs has been significantly improved by the new embedding packaging structure. The die-bonding interface thermal resistance can be reduced by more than 20%. The junction temperature rise can be reduced by 14%. Due to the fully embedding of LED chip in the square groove, the light intensity distribution is slightly shrunk and the light output power is slightly reduced by about 8%.

Orange-red-emitting CaTi4(PO4)6:Eu3+ phosphor for white LEDs: synthesis and luminescence properties

Cao Renping,Shao Wenhua,Zhao Yanshu,Chen Ting,Ao Hui,Guo Siling,Liu Pan,Fan Ting

CaTi 4 (PO 4 ) 6 : x Eu 3+ phosphors are successfully synthesized under air condition by high-temperature solid-state method. The crystal structure, morphology, energy spectrum, atomic percentage, elemental mapping, and luminescence properties are investigated, respectively. Monitored at 594 nm, the excitation spectral bands of CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor in the range of 210–550 nm are assigned to the O 2− –Eu 3+ charge transfer band (CTB) and the 7 F 0  →  5 H 3 , 5 L 7 , 5 L 6 , 5 D 1 , 5 D 2 , 5 D 3 , and 5 D 4 transitions of Eu 3+ ion. With excitation at 394 nm, CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor emits orange-red light with the chromaticity coordinates (0.548, 452), and the emission spectral bands in the region from 575 to 720 nm are attributed to the 5 D 0  →  7 F 1 , 7 F 2 , 7 F 3 , and 7 F 4 transitions of Eu 3+ ion. The optimal doping concentration of Eu 3+ ion is ~ 8 mol%. The lifetime of CaTi 4 (PO 4 ) 6 :Eu 3+ phosphors decreases from 1.87 to 0.97 ms with increasing Eu 3+ concentrations from 1 to 10 mol%. CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor has a good thermal stability. The experimental results indicate that CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor has an application prospect in white light-emitting diodes (LEDs) based on the near ultraviolet (~ 394 nm) LED chip.

Photometric Optimization of Color Temperature Tunable Quantum Dots Converted White LEDs for Excellent Color Rendition

Wu Yang,Ping Zhong,Shiliang Mei,Qiuhang Chen,Wanlu Zhang,Jiatao Zhu,Ruiqian Guo,Guoxing He

A high efficient and anti-thermal dual-emission blue-green phosphors for warm white LEDs

Liu Dong,Jin Yahong,Xiong Guangting,Lv Yang,Wu Haoyi,Ju Guifang,Chen Li,Hu Zhengfa,Hu Yihua

A series of broadband blue-green phosphors Rb 0.5+ y Na 1.5− y (Li 3 SiO 4 ) 2 : x Eu 2+ (0 ≤  y  ≤ 0.4, 0.01 ≤  x  ≤ 0.08) were synthesized by the high-temperature solid-state reaction. The powder X-ray diffraction was employed to explore the crystal structural evolution from RbNa 3 (Li 3 SiO 4 ) 4 to RbNa(Li 3 SiO 4 ) 2 with the increasing of Rb + . The spectra show the optimized composition was determined as y  = 0.4. The luminescence, lifetime decay curves and thermal steadily spectra of Rb 0.9 Na 1.1 (Li 3 SiO 4 ) 2 : x Eu 2+ phosphors were investigated in detail. The phosphor of Rb 0.9 Na 1.1 (Li 3 SiO 4 ) 2 :Eu 2+ shows suitable visible spectra (450–550 nm, cover the blue and green regions), excellent thermal quenching (104%@150 °C of the initial integrated intensity at room temperature under 396 nm excitation) and broad excitation spectrum (320–450 nm). Finally, a commercial near-UV LED devices (395 nm) were fabricated with the Rb 0.9 Na 1.1 (Li 3 SiO 4 ) 2 :Eu 2+ phosphor as blue-green and commercial red phosphor CaAlSiN 3 :Eu 2+ with a warm color temperature of 3104 K and a color rendering index of 91.8. This result indicated that Rb 0.9 Na 1.1 (Li 3 SiO 4 ) 2 :Eu 2+ may be a promising blue-green phosphor for indoor lighting.