Luminous efficacy enhancement for LED lamps using highly reflective quantum dot-based photoluminescent films.

In this study, a strongly reflective and photoluminescent (PL) poly(lactic-co-glycolic acid) quantum dot (QD) hybrid nanofiber (PQHN) structure is introduced to enhance the luminous efficacy of QD-phosphor hybrid white light-emitting diodes (QD-WLEDs). As the thickness of PQHN film increases, the PL is found to continuously increase, exhibiting a maximum peak intensity at 120 μm, which is 1.92 times that at 12 μm, and showing the highest diffuse reflectance of 94.

Optical Performance and Moisture Stability Enhancement of Flexible Luminescent Films Based on Quantum-Dot/Epoxy Composite Particles.

Quantum dots (QDs) have been widely applied in luminescent sources due to their strong optical characteristics. However, a moisture environment causes their quenching, leading to an inferior optical performance in commercial applications. In this study, based on the high moisture resistance of epoxy resin, a novel epoxy/QDs composite particle structure was proposed to solve this issue.

Phosphor-in-glass (PIG) converter sintered by a fast Joule heating process for high-power laser-driven white lighting.

Currently, laser-driven lighting based on phosphor-in-glass (PIG) has drawn much interest in solid state lighting due to its high electro-optical efficiency and high-power density. However, the fabrication of PIG requires expensive equipment, long sintering time, and high cost. In this work, we utilized a simple, fast, and high temperature Joule heating process to make phosphor-in-glass bulk sintered in less than 20 s, which greatly improved the production efficiency.

White hairy layer on the Boehmeria nivea leaf-inspiration for reflective coatings.

Whiteness is an intriguing property in some creature surfaces and usually originates from broadband multi-scattering by the refined structures. In this article, we report that Boehmeria nivea, a widely distributed tropical and subtropical plant, has a highly reflective layer on the lower surface of the leaf. Morphological characterization demonstrates that the layer consists of numerous wrinkled micro-filaments, forming a disordered porous network to efficiently scatter visible light.

Ultrasonication-assisted synthesis of CsPbBr and CsPbBr perovskite nanocrystals and their reversible transformation.

We demonstrate an ultrasonication-assisted synthesis without polar solvent of CsPbBr and CsPbBr perovskite nanocrystals (PNCs) and their reversible transformation. The as-prepared CsPbBr PNCs and CsPbBr PNCs exhibit different optical properties that depend on their morphology, size, and structure. The photoluminescence (PL) emission and quantum yield (QY) of the CsPbBr PNCs can be tuned by changing the ultrasound power, radiation time, and the height of the vibrating spear.

Microlens arrays with adjustable aspect ratio fabricated by electrowetting and their application to correlated color temperature tunable light-emitting diodes.

We develop a facile, fast, and cost-effective method based on the electrowetting effect to fabricate concave microlens arrays (MLA) with a tunable height-to-radius ratio, namely aspect ratio (AR). The electric parameters including voltage and frequency are demonstrated to play an important role in the MLA forming process. With the optimized frequency of 5 Hz, the AR of MLA are tuned from 0.

Enhancement of luminous efficacy for LED lamps by introducing polyacrylonitrile electrospinning nanofiber film.

Polyacrylonitrile electrospinning nanofiber film was introduced into a light emitting diode (LED) lamp to exploit the strong reflective and scattering effects. The light extraction mechanism was studied systematically for three different electrospinning types in three different types of LED lamps. For the all-electrospinning types, the luminous efficacy increased for the white LED, outwards remote phosphor layer, and inwards remote phosphor layer lamps by 10.

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

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.

Efficient synthesis of highly fluorescent carbon dots by microreactor method and their application in Fe ion detection.

Rapidly obtaining strong photoluminescence (PL) of carbon dots with high stability is crucial in all practical applications of carbon dots, such as cell imaging and biological detection. In this study, we proposed a rapid, continuous carbon dots synthesis technique by using a microreactor method. By taking advantage of the microreactor, we were able to rapidly synthesized CDs at a large scale in less than 5min, and a high quantum yield of 60.

Color uniformity enhancement for COB WLEDs using a remote phosphor film with two freeform surfaces.

The color uniformity (CU) of chip-on-board (COB) white light emitting diodes (WLEDs) has been improved by using remote phosphor films with two freeform surfaces (TFS-RPFs). The finite-difference time-domain (FDTD), Monte Carlo ray-tracing, and color-thickness feedback (CTFB) methods were used to design the TFS-RPFs: the blue light distribution of COB WLEDs is greatly affected by the angular thickness distribution of TFS-RPFs, and a high CU can be achieved iteratively. The directional inconsistency of incident and emergent blue light, scattering effect of TFS-RPFs, and illumination characteristics of the COB source were also investigated.