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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.

Disordered porous polymer structures have gained tremendous attention due to their wide applications in various fields. As a simple yet versatile technique, supercritical C O 2 microcellular foaming has been proposed to fabricate highly scattering porous polymer films, which have been used to enhance the efficiency of quantum dots (QDs) films. In the foaming process, numerous enclosed pores are generated, which induce significant scattering, underpinning the efficiency enhancement in optoelectronic devices. However, the scattering property of foamed porous structures has still not been well investigated, and effective guidelines for engineering the porous structures are still not available. In this work, we use Mie scattering theory and ray-tracing simulation to analyze the optical property of a single pore, pore assembly, and porous film. Furthermore, it is demonstrated that the scattering scheme in the porous QD films leads to a large enhancement of excitation light absorption and QD emission extraction. It is envisioned that our work will contribute to the engineering guidelines of porous structures and boost the application of porous structures in similar fields.

Although quantum dots (QDs) have a high quantum yield close to one in a solution, they exhibit low conversion efficiency in a solidification polymer matrix, which hampers the development of QD-based light-emitting diodes (LEDs) with high stability and optical performance. In this study, we proposed a methyl-terminated-polydimethylsiloxane-(PDMS)-based liquid-type packaging structure (LPS) to improve stability and optical performance of QD-based LEDs. Compared with the traditional ethylene-terminated-PDMS-based solid-type packaging structure, the LPS with an optimized kinematic viscosity of 10000  m 2 /s can provide higher stability and optical performances for QD-based LEDs, including total radiant power and luminous flux. Consequently, the proposed effective and simple strategy has great potential for illumination and display applications.

Inspired by the Papilio blumei butterfly, quantum-dot (QD) film coupled with micro-concavity array (MCA) films is proposed in this Letter to enhance color conversion efficiency (CCE) of QD-based light-emitting diodes (LEDs). The diameter, aspect ratio, and pitch of the MCA are optimized in the optical simulations. Both the simulation and experimental results show that the scattering and double reflection effects are the key to the CCE improvement of QD films. The results show that the CCEs are increased from 19.98% to 21.59% and 21.78% (350 mA) for single-sided microstructured QD film and double-sided microstructured QD film configurations, respectively. Overall, the MCA film is a promising solution to enhance the CCE of QD-based LEDs.

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 BaSO 4 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.

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.