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Your search keyword '"Rao, Longshi"' showing total 6 results
Start Over Author "Rao, Longshi" Journal optics express
6 results on '"Rao, Longshi"'

2. Highly reflective nanofiber films based on electrospinning and their application on color uniformity and luminous efficacy improvement of white light-emitting diodes

Author

Rao Longshi, Chen Junchi, Yong Tang, Zongtao Li, Guanwei Liang, Yu Shudong, and Binhai Yu

Subjects
Materials science, business.industry, Scattering, 02 engineering and technology, Color temperature, engineering.material, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic and Molecular Physics, and Optics, Electrospinning, 010309 optics, Optics, Coating, Nanofiber, 0103 physical sciences, engineering, Optoelectronics, Diffuse reflection, Fiber, 0210 nano-technology, Luminous efficacy, business
Abstract

Based on electrospinning technology, in this study, we fabricated poly(lactic-co-glycolic acid) (PLGA) nanofiber films with high reflectivity and scattering properties. Various films with different thicknesses and fiber diameters were fabricated by changing the electrospinning time and solution concentration, respectively. Detailed optical measurements demonstrate that the film reflectance and scattering ability increase with the thickness, whereas fiber diameter contributes little to both properties. With optimized film thickness and fiber diameter, nanofiber films feature whiteness with a reflectance of 98.8% compared to the BaSO4 white plate. Furthermore, when deposited on the reflector surface of a remote phosphor-converted light-emitting diode lamp, nanofiber films witness a correlated color temperature deviation decrease from 8880 K to 1407 K and a luminous efficiency improvement of 11.66% at 350 mA. Therefore, the nanofiber films can be applied in lighting systems as a highly reflective coating to improve their light efficacy and quality.

Published
2017

3. Effect of ZnO nanostructures on the optical properties of white light-emitting diodes

Author

Zongtao Li, Hangaung Lu, Xinrui Ding, Yong Tang, Caiman Yan, Jiasheng Li, Yu Shudong, and Rao Longshi

Subjects
Materials science, business.industry, Scattering, Doping, Phosphor, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic and Molecular Physics, and Optics, Light scattering, law.invention, 010309 optics, Luminous flux, Optics, law, 0103 physical sciences, 0210 nano-technology, business, Refractive index, Diode, Light-emitting diode
Abstract

White light produced by blue LEDs with yellow phosphor is the most widely used methods, but it results in poor quality in angular CCT uniformity. In this work, a novel technique was introduced to solve this problem by integrating different ZnO nanostructures into white light-emitting diodes. The experiment of ZnO doped films and the simulation of Finite-Difference Time-Domain (FDTD) were carried out. The result indicated scattering effect of ZnO nanoparticles could improve uniformity of scattering energy effectively. Moreover, the effect of ZnO nanostructures on white light-emitting diodes (wLEDs) devices was also investigated. The CCT deviation of wLEDs devices would decrease from 3455.49 K to 96.30 K, 40.03 K and 60.09 K when the node-like (N-ZnO), sheet-like (S-ZnO) and rod-like ZnO (R-ZnO) respectively applied. The higher CCT uniformity and little luminous flux dropping were achieved when the optimal concentrations of N-ZnO, S-ZnO, and R-ZnO nanostructures were 0.25%, 0.75%, and 0.25%. This low-cost and green manufacturing method has a great impact on development of white light-emitting diodes.

Published
2017

6. Highly emissive green CsPbBr 3 /Cs 4 PbBr 6 composites: formation kinetics, excellent heat, light, and polar solvent resistance, and flexible light-emitting application.

Author

Rao L, Sun B, Zhang Q, Wen M, Zhang J, Zhong G, Fu T, Niu X, and Tang Y

Abstract

Benefit from their near-unity photoluminescence quantum yield (PL QY), narrow emission band, and widely tunable bandgap, metal halide perovskites have shown promising in light-emitting applications. Despite such promise, how to facile, environmentally-friendly, and large-scale prepare solid metal halide perovskite with high emission and stability remains a challenging. Herein, we demonstrate a convenient and environmentally-friendly method for the mass synthesis of solid CsPbBr 3 /Cs 4 PbBr 6 composites using high-power ultrasonication. Adjusting key experimental parameters, bright emitting CsPbBr 3 /Cs 4 PbBr 6 solids with a maximum PL QY of 71% were obtained within 30 min. XRD, SEM, TEM, Abs/PL, XPS, and lifetime characterizations provide solid evidence for forming CsPbBr 3 /Cs 4 PbBr 6 composites. Taking advantage of these composites, the photostability, thermostability, and polar solvent stability of CsPbBr 3 /Cs 4 PbBr 6 are much improved compared to CsPbBr 3 . We further demonstrated CsPbBr 3 /Cs 4 PbBr 6 use in flexible/stretchable film and high-power WLEDs. After being subjected to bending, folding, and twisting, the film retains its bright emission and exhibits good resistance to mechanical deformation. Additionally, our WLEDs display a superior, durable high-power-driving capability, operating currents up to 300 mA and maintaining high luminous intensity for 50 hours. Such highly emissive and stable metal halide perovskites make them promising for solid-state lighting, lasing, and flexible/stretchable display device applications.

Published
2022
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