Stable and Efficient Green Perovskite Nanocrystal-Polysilazane Films for White LEDs Using an Electrospray Deposition Process

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 94.4% at 640 nm. Consequently, while using the QD-WLEDs, the PQHN structure achieves a 53.8% improvement in luminous flux compared with the traditional structure under a similar correlated color temperature (CCT) of 3,540 K, achieving a high luminous efficacy of 202.11 lm W^-1 for QD-WLEDs. In addition, the maximum deviation of the CCT is only 11 K when the current is changed from 50 to 950 mA, demonstrating good stability. Therefore, the PQHN films have great potential in lighting systems as a hybrid functional film including light conversion and reflectance.

State of the Art and Prospects for Halide Perovskite Nanocrystals

Metal-halide perovskites have rapidly emerged as one of the most promising materials of the 21st century, with many exciting properties and great potential for a broad range of applications, from photovoltaics to optoelectronics and photocatalysis. The ease with which metal-halide perovskites can be synthesized in the form of brightly luminescent colloidal nanocrystals, as well as their tunable and intriguing optical and electronic properties, has attracted researchers from different disciplines of science and technology. In the last few years, there has been a significant progress in the shape-controlled synthesis of perovskite nanocrystals and understanding of their properties and applications. In this comprehensive review, researchers having expertise in different fields (chemistry, physics, and device engineering) of metal-halide perovskite nanocrystals have joined together to provide a state of the art overview and future prospects of metal-halide perovskite nanocrystal research.

Effect of Confinement on the Exciton and Biexciton Dynamics in Perovskite 2D-Nanosheets and 3D-Nanocrystals

The performance of the high-end optoelectronic devices is essentially influenced by the intrinsic relaxation mechanisms pursued by the hot carriers. Therefore, the key toward achieving progression in such fields lies in developing a complete understanding of the involved carrier cooling dynamics. In this work, an endeavor has been made to highlight the difference in the cooling mechanisms in 2D CsPbBr₃ nanosheets (NSs) and their 3D counterpart nanocrystals (NCs) with the aid of femtosecond broad-band pump-probe spectroscopy, varying the excitation energies. The exciton and biexciton dynamics in both systems are found to be retarded upon increasing the excitation energy. However, in contrast to 3D NCs, carrier cooling is found to be faster in the 2D system, regardless of the excitation energy used, attributing this to less efficient charge screening by Fröhlich interaction in low-dielectric medium. A similar trend is replicated in the biexciton formation rate since the formation is also found to be faster in NSs compared to NCs.

Highly efficient and stable CsPbBr3 perovskite quantum dots by encapsulation in dual-shell hollow silica spheres for WLEDs

A highly stable and efficient CsPbBr₃@SiO₂ composite phosphor is achieved by protecting the CsPbBr₃ QDs from direct exposure to the atmosphere by encapsulating CsPbBr₃ into dual-shell hollow silica nanospheres.