Smart white lighting and multi‐mode optical modulations via photochromism in Dy‐doped KNN‐based transparent ceramics

Abstract

Compared to common incandescent and fluorescent lamps, solid-state lighting (SSL) has gained tremendous attention owing to their high luminous efficiency, high brightness, low power consumption and long lifetime. 1-4 Lightemitting diodes (LEDs) in SSL sources exhibit widespread applications in backlighting displays, data communications, medical devices, barcode scanners, and signals. 5,6 White light is commonly obtained by the excitation of either ultraviolet (UV) or blue emitting LED chips that encapsulate phosphors in an epoxy resin. However, phosphors coated on the chips are easily deteriorated due to heating, contacting with organic solvents or re-absorption of blue light, reducing the quality of emitted light. 7,8 Meanwhile, phosphors own lower thermal conductivity and higher surface energy than that of bulk counterparts, partly reducing the emission efficiency and lifetime of LEDs. Therefore, it is of great interest to develop bulk materials with the advantages of simple packaging, good thermal stability, and high efficiency of heat conduction for LEDs. Nonetheless, frequently studied bulk luminescent materials are concentrated in glass-ceramics, such as Y 3 Al 5 O 12 (YAG) and the derivatives. 9-11 To expand the functionalities in LEDs, especially WLEDs, it is of significance to explore novel luminescent bulks.

Expedient Red Emitting and Transparency Dual Modulation in KNN-Based Transparent Ceramics via Sensitive Photothermochromic Behavior

“…Figure d–f show that the modulation of the red emitting of the KNNEB transparent ceramics exhibits excellent stability under the continuous alternating of irradiation (395 nm, 300 W, 1 min) and heat treatment (200 °C, 10 min) for 10 cycles, as stable as the modulation of transmittance analyzed above. Taken together, compared with the previously reported luminescent KNN transparent PC ceramics, ,,− the KNNEB ceramics hold absolute advantages in terms of the excellent transparency and the modulation of optical properties, which are manifested in the following two aspects: (1) moderate contrast of optical properties based on PTC behavior while ensuring excellent transparency (Figure ) and (2) unique high-purity red emitting characteristics and corresponding modulation. These notable properties create application prospects for the KNNEB transparent ceramics in the fields of multifunctional transparent sustainable warning equipment and optical storage materials.…”

Defect Management and Multi‐Mode Optoelectronic Manipulations via Photo‐Thermochromism in Smart Windows

“…Of particular importance is that the Δ R values of the Er‐KNN‐BST transparent ceramics are in lead position in opaque ferroelectric ceramics, [ 43,50–68 ] as depicted in Figure . Simultaneously, both the Δ R values and transmittances of them are much higher than the reported transparent ferroelectric ceramics, [ 17,34,47,68–75 ] exhibiting great potential in the application of information storages in smart windows.…”

Significantly Photo‐Thermochromic KNN‐Based “Smart Window” for Sustainable Optical Data Storage and Anti‐Counterfeiting

“…[33] To date, the PTC behavior of the Er-KNLN ceramics (especially for Er-KNLN-1150 and Er-KNLN-1165) can compete with the opaque luminescent ferroelectric PC ceramics (Figure 5a), [3,14,15,17,18,31,34,35] simultaneously, their excellent transparency and modulations of optical properties exhibit prominent advantages compared with the previously reported luminescent KNN transparent PC ceramics (Figure 5b). [13,19,20,[36][37][38][39]…”