LED has the advantages of high efficiency, energy saving and environmental protection. It is widely used in the field of lighting. Improving the luminous efficiency of LED has always been a research difficulty and hot spot in this field. To reduce the total reflection phenomenon between GaN material and air and to improve the light extraction efficiency, fabrication and properties of the anodized aluminum oxide (AAO) nanostructured LED device were studied. Through inductively coupled plasma (ICP) etching process, large-area ordered pore nanostructure arrays were successfully fabricated on the surface of p-GaN layer, and the quasi-photonic crystal structure with apertures of 250-500 nm and pore depths of 50-150 nm were obtained. The crystal structure greatly increases the luminous intensity of the LED, and the nano-array LED with pore diameter of 400 nm and depth of 150 nm is improved by 3.5 times in contrast to the LED without the nano-array.

LiLuF₄ single crystals doped with Ce ³⁺ ion of 0.1mol% and Yb ³⁺ ion of concentration varying from 0 to 2.0mol% were successfully synthesized by an improved Bridgman method. Intense near-infrared emission at around 1020 nm, attributed to the ²F_5/2→ ²F_7/2 transition of Yb ³⁺, and ultraviolet emission of Ce ³⁺ at 300-350 nm (5d→4f) was observed using excitation at 291 nm. Influence of Yb ³⁺ ions concentration on the spectroscopic properties of Ce ³⁺/Yb ³⁺ co-doped LiLuF₄ single crystal and the mechanism of energy transfer from Ce ³⁺ to Yb ³⁺ ions were explored through optical absorption and emission spectra. The temperature dependent emission indicated that the emission intensity constantly decreases with the increase of temperature from 298 to 443 K due to the enhancement of non-radiative quenching at high temperature. Ce ³⁺/Yb ³⁺ co-doped LiLuF₄ single crystals mainly emit in the ultraviolet and near-infrared ranges. This unique property may be suitable for applications in anti-counterfeiting techniques and public security affairs.

Chromogenic materials are capable of optical change reversibly in response to physical stimuli (e.g., electric field, temperature, illumination, and atmosphere). Among them, electrochromic materials are expected to be widely used in smart windows, screen displays, multi-functional energy storage devices and other fields due to their characteristics such as large adjustment range, fast response rate, high coloring efficiency and good cycle stability. However, compared with semi-solid-state electrochromic devices that are difficult to package and organic electrochromic materials that are prone to denaturation and failure, inorganic all-solid-state electrochromic materials and devices have better comprehensive application. This paper focuses on the typical inorganic all-solid-state electrochromic materials and devices, presents a brief review on the current preparation methods of each structure layer of electrochromic devices and compares its advantages and disadvantages, introduces in detail the main alternative electrochromic materials and its key performance evaluation index, and explains the principle of several representative electrochromic devices, proposes to use transparent flexible electrodes with both high light transmittance, low surface resistance and excellent bending fold to replace the traditional rigid substrate in order to realize multi-field responsible device application development. Finally, the application prospect of inorganic all-solid-state electrochromic devices is prospected from the perspective of performance bottleneck, process difficulty and industrialization opportunity, which provides reference for the industrialization process of electrochromic devices.

NaBiF₄:Yb³⁺/Er³⁺ upconversion materials modified by different organic ligands were synthesized by solvent thermal method, and then their morphology and luminescence properties were studied. The results show that the soft template and orientation of the organic ligands can tune the particle size and morphology of the UCNPs, and the defect passivation of the surface organic ligands enhances the luminescence intensity. Especially, the cetyl trimethylammonium bromide (CTAB) and the cetyl trimethylammonium chloride (CTAC) modified materials have the most significant enhancement effect (9 times). Furthermore, the effects of temperature and pH on luminescent properties of the materials were investigated. Results show that, within the range of experimental conditions, the luminescence intensity of the materials decreases with the increase of temperature from 30 to 90 ℃ and significantly reduces under strong acid and alkaline conditions, with maximum at pH 5-6.

Cu-In-Zn-S (CIZS) quantum dots (QDs) are considered as promising fluorescent materials owing to their low toxicity, wide emission range and large Stokes shifts, which have a wide prospect in lighting field. CIZS QDs were prepared via ionic liquid assisted microwave method in aqueous solution. The effects of reaction time, addition amount of ligand and pH of precursor solution on phase composition, microscopic morphology and photoluminescence (PL) property were investigated. Results showed that the reaction rate could be accelerated with the assistance of ionic liquid, i.e. the reaction time reducing from 180 min to 30 min. The size of QDs gradually increased with the increase of reaction time, resulting in red shift of emission peak from 609.2 to 634.6 nm. Moreover, the particle size of CIZS QDs increased with the increase of n_GSH/n_(CuInZn) ratios, resulting in the red shift of emission peak from 622.6 nm to 631.6 nm. Meanwhile, the PL intensity of QDs increased and reached the maximum at n_GSH/n_(CuInZn)=15. Furthermore, the surface defect state was effectively passivated with the increase of pH of precursor solution due to enhanced bonding force between deprotonized groups (-SH, -NH₂) and QDs, resulting in enhancement of PL intensity. And the optimal pH was 8.5. The average hydrodynamic size of CIZS QDs increased from 99 nm to 241 nm with the increase of pH, and the relative Zeta potential ranged from -27.7 mV to -41.1 mV, indicating the excellent stability of CIZS QDs solution. Emission intensity of QDs could be enhanced significantly after coating with ZnS shells. White LED device was fabricated by combining CIZS QDs and a blue chip, the color rendering index and luminous efficiency of device were 85.6 and 34.8 lm/W, respectively, which provided a reference for the application of water soluble multiple QDs in white LEDs.

Rare-earth doped inorganic ferroelectrics are considered as novel photochromic materials, with potential applications for optical switch and information storage (K_0.5Na_0.5)_1-xEu_xNbO₃ (KNN:xEu) ceramics were prepared by high temperature calcination, with precursor powder obtained by hydrothermal method. Strong red emission at 615 nm was observed which corresponds to the ⁵D₀→ ⁷F₂ transition of Eu ³⁺ under excitation of 465 nm. Under UV light irradiation for 3 min, the color of the ceramics turned from milky white to dark gray. The colored samples returned to the original color when heated at 200 ℃ for 10 min, showing strong photochromic behavior. Meanwhile, the luminescence intensity of Eu ³⁺ can be tuned without obvious degradation by alternating UV light and heat stimulus. Upon UV light irradiation, large luminescence modulation ratio (ΔR_t) up to 83.9% was achieved for KNN:0.06Eu, indicating good luminescence switching behavior. A possible mechanism for non-radiative energy transfer from the luminescent center to the color center was proposed according to their luminescent behavior.