Search

CsPbBr3@Ag hybrid nanocrystals are synthesized for the first time by reacting CsPbBr3 nanocrystals with AgX (X = Cl, Br, or I) powders in hexane. The morphologies of the hybrid nanocrystals showed that 2–5 nm Ag nanoparticles were nucleated randomly outside the CsPbBr3 nanocrystals, which indicated that Ag+ ions released by AgX powders could be reduced to Ag0 by surfactant ligands of CsPbBr3 nanocrystals and aggregated to Ag nanoparticles. Significant enhancement of the photoluminescence intensity of CsPbBr3@Ag hybrid nanocrystals was observed compared with that of pure CsPbBr3 nanocrystals under the excitation of 400 nm light, which was mainly attributed to the enhanced absorbance of ultraviolet or blue light by the Ag induced plasmonic near-field effect. Numerical simulations showed that CsPbBr3@Ag hybrid nanocrystals provided intense local field amplification at the perimeter of Ag nanoparticles. However, Ag adhesion can also cause the deteriorating surface quality of CsPbBr3 nanocrystals, and in turn reduce photoluminescence quantum yield. Therefore, Ag adhesion has two completely different influences on the photoluminescence of hybrid perovskite quantum dots. To achieve an enhanced photoluminescence, we have to optimize CsPbClxBr3−x@Ag hybrid nanocrystals so that the effect of plasmonic resonance enhancement occupied a significantly advantageous position. The surface trap states served as a nonradiative relaxation pathway for the photogenerated charge carriers and decreased the emission quantum yield of the hybrid nanocrystals. This suggests that a potential issue concerning the performance of CsPbBr3@Ag hybrid nanocrystals was a trade-off between enhanced light absorbance of CsPbBr3@Ag hybrid nanocrystals and reduced photoluminescence due to energy transfer from CsPbBr3 nanocrystals to Ag nanoparticles. This simple method to construct CsPbBr3@Ag hybrid nanocrystals offers new opportunities to enhance optical properties and expand the application of perovskite quantum dots for light emitting diodes and other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Inorganic CsPbI 3 perovskite nanocrystals (NCs) exhibit remarkable optoelectronic properties for illumination. However, their poor stability has hindered the development of light-emitting diodes (LEDs) based on these materials. In this study, we propose a facile method to synthesize Mg 2+ -doped CsPbI 3 NCs with enhanced stability and high photoluminescence (PL) intensity under ambient air conditions. Theoretical calculations confirm that doped NCs possess stronger formation energy compared to undoped NCs. The undoped CsPbI 3 NCs emit red light at approximately 653 nm. We optimize the doping ratio to 1/30, which significantly enhances the photoluminescence of single-particle CsPbI 3 NCs. Subsequently, we fabricate a red LED by combining the CsPbI 3 NCs with a blue chip. The resulting LED, based on the doped CsPbI 3 NCs, exhibits excellent performance with a high luminance of 4902.22 cd m -2 and stable color coordinates of (0.7, 0.27). This work not only presents a simple process for synthesizing perovskite NCs but also provides a design strategy for developing novel red LEDs for various applications.

Lead halide perovskite nanocrystals with efficient two-photon absorption and ease of achieving population inversion have been recognized as good candidates to achieve frequency up-conversion for biophotonics applications, but suffer from the limitation of the miniaturization of the device and its corresponding poor stability when exposed to atmospheric moisture. Here we demonstrate the miniaturization of plasmonic nanolasers via embedding perovskite quantum dots (QDs) in rationally designed dual-mesoporous silica with gold nanocore. The nanocomposite supports resonant surface plasmon-polaritons (SPPs), which overlap both spatially and spectrally with the CsPbBr3 QDs. The outcoupling between surface plasmon oscillations and photonics modes within a wavelength range completely overcomes the loss of localized surface plasmons, and finally contributes to a novel application of two-photon-pumped nanolasers. Large optical gain under two-photon excitation was observed as a result of resonant energy transfer from excited perovskite QDs to surface plasmon oscillations and stimulated emission of surface plasmons in a luminous mode. The outmost organic-inorganic hybrid shells of the dual-mesoporous silica nanocomposites act as a protective layer of the perovskite QDs against water and endow the nanocomposites with superhydrophobicity. This work provides an alternative inspiration for the design of new two-photon pumped nanolasers.