There are many strategies to maintain the excellent photoluminescence (PL) characteristics of perovskite quantum dots (QDs). Here, we proposed a facile and effective method to prepare cyan CsPb(Cl/Br)₃/SiO₂ nanospheres at room temperature. Cubic CsPb(Cl/Br)₃ was obtained by adding a LiCl-H₂O solution and anion exchange reaction. With (3-aminopropyl)triethoxysilane as an auxiliary agent, a QDs/SiO₂ composite was extracted from a sol-gel solution by precipitate-encapsulation method. The transmission electron microscopy images and Fourier transform infrared spectra indicated the QDs were indeed embedded in silica substances. Besides, humidity stability and thermal stability show the composite possesses a great application value. Finally, cyan QDs@SiO₂ powder has a high PL quantum yield of up to 84%; the stable cyan fluorescent powder does have great potential to play a key role in commercial full spectrum display.

To introduce ordered nano-structures inside a transparent amorphous matrix with superior optical and mechanical properties bears scientific and technological importance, yet limited success has been achieved. Here, via simple melting-quenching and subsequent thermal activation, we report the successful preparation of transparent nano-structured glass-ceramics embedded in Sr₂LuF₇ nano-crystals (～26 nm), as evidenced by X-ray diffraction, transmission electron microscopy (TEM), and high resolution TEM. The successful incorporation of dopants into formed Sr₂LuF₇ nano-crystals with low phonon energy results in highly tunable blue–green photoemission, which depends on excitation wavelength, dopant type, and temperature. We found that Eu³⁺ and Eu²⁺ ions co-exist in this hybrid optical material, accompanied by the broadband blue emission of Eu²⁺ and sharp red emissions of Eu³⁺. A series of optical characterizations are summoned, including emission/excitation spectrum and decay curve measurement, to reveal the reduction mechanism of Eu³⁺ to Eu²⁺. Furthermore, near green–white photoemission is achieved via the enrichment of Tb³⁺/Eu³⁺ into crystallized Sr₂LuF₇ nano-crystals. The temperature-dependent visible photoemission reveals thermal activation energy increases with the precipitation of Sr₂LuF₇ nano-crystals in a glass matrix, suggesting better thermal stability of glass-ceramics than precursor glasses. These results could not only deepen the understanding of glass-ceramics but also indicate the promising potential of Eu³⁺/Tb³⁺-ions-doped Sr₂LuF₇ glass-ceramics for UV pumped white light emitting diodes (WLEDs) with good thermal stability.

The design of a conventional zoom lens is always challenging because it requires not only sophisticated optical design strategy, but also complex and precise mechanical structures for system adjustment. Here, we propose a continuous-zoom lens consisting of two chiral geometric metasurfaces with dielectric nanobrick arrays sitting on a transparent substrate. The metalens can continuously vary the focal length by rotating either of the two metasurfaces around its optical axis without changing any other conditions. Due to the polarization dependence of the geometric metasurface, the positive and negative polarities are interchangeable in one identical metalens only by changing the handedness of the incident circularly polarized light, which can generate varying focal lengths ranging from ∞ to +∞ in principle.

In this work, Er-doped aluminum nitride (AlN), Pr-doped AlN, and Er, Pr co-doped AlN thin films were prepared by ion implantation. After annealing, the luminescence properties were investigated by cathodoluminescence. Some new and interesting phenomena were observed. The peak at 480 nm was observed only for Er-doped AlN. However, for Er, Pr co-doped AlN, it disappeared. At the same time, a new peak at 494 nm was observed, although it was not observed for Er-doped AlN or Pr-doped AlN before. Therefore, the energy transfer mechanism between Er³⁺ and Pr³⁺ in AlN thin films was investigated in detail. Through optimizing the dose ratio of Er³⁺ with respect to Pr³⁺, white light emission with an International Commission on Illumination chromaticity coordinate (0.332, 0.332) was obtained. This work may provide a new strategy for realizing white light emission based on nitride semiconductors.

Ho³⁺/Yb³⁺: BaMoO₄ phosphors with different concentrations were fabricated by a gel combustion method. The upconversion (UC) luminescence, intrinsic optical bistability, and the corresponding mechanisms were reported for the present system. The optical thermometric properties based on red (⁵F₅→⁵I₈) and green (⁵F₄/⁵S₂→⁵I₈) emissions were studied. The sensing sensitivities could be tuned by manipulating the cooperative energy transfer process. The highest absolute sensitivity was 99 × 10 ⁴ K ¹ at 573 K, which is larger than that of many previous UC materials.

Phosphor in glass (PiG) employing Ce:Y₃Al₅O₁₂ (YAG)-doped boro-bismuthate glass via low-temperature co-sintering technology was successfully prepared, using Bi₂O₃-B₂O₃-ZnO glass as the base material. The photoluminescence (PL) of PiG co-sintered at times ranging from 20 min to 60 min at 700°C was investigated. As a result, the relative PL intensity of PiG under a reducing atmosphere of CO showed significant enhancement of about 7–14 times that under air atmosphere sintering for 20–50 min. The PL intensity decreased gradually with the co-sintering time, which may be due to the corrosion of the YAG lattice structure.

Yb³⁺/Er³⁺ co-doped Na₅Lu₉F₃₂ single crystals used as a spectral up-converter to improve the power conversion efficiency of perovskite solar cells are prepared via an improved Bridgman approach. Green and red up-conversion (UC) emissions under the excitation of near-infrared (NIR) bands of 900–1000 nm and 1400–1600 nm can be observed. The effectiveness of the prepared materials as a spectral converter is verified by the enhancement of power conversion efficiency of perovskite solar cells. The sample with a UC layer is 15.5% more efficient in converting sunlight to electricity compared to the UC layer-free sample due to the absorption of sunlight in the NIR range. The results suggest the synthesized Yb³⁺/Er³⁺ co-doped Na₅Lu₉F₃₂ single crystals are suitable for enhancing the performance of perovskite solar cells.

The ultrafast spin dynamic of in-plane magnetized Fe/Pt films was investigated by terahertz emission spectroscopy. The amplitude of the emitted terahertz wave is proportional to the intensity of the exciting laser beams. Both the amplitude and polarity of the terahertz wave can be adjusted by modifying the external magnetic field. The dependency of the amplitude on external magnetic fields is coincident to the hysteresis loops of the sample. Also, the polarity of the terahertz wave is reversed, as the magnetization orientation is reversed. The super-diffusive transient spin current with an inverse spin Hall effect is attributed to the main mechanism of the terahertz emission.