Ultraviolet-B and Near-Infrared Dual-Band Luminescence in Bi<sup>3+</sup>/Bi<sup>2+</sup> Codoped Persistent Phosphor for Optical Storage Application
Shihai Miao, Xulong Lv, Xihui Shan, Yi Zhang, Yanjie Liang
Abstract
Discovering multifunctional luminescent materials to meet the demands of modern spectroscopy is of great significance. However, it is a standing challenge to enable multiple luminescence properties in a single material system via single metal ion doping. Here, we report the inherently Bi 3+ /Bi 2+ codoped Ca 3 Ga 2 Ge 3 O 12 persistent phosphor where Bi 3+ is in situ reduced to Bi 2+ . This phosphor can act as an efficient multimodal luminescence material, which simultaneously exhibits long-lasting (>12 h) ultraviolet-B (UVB) and near-infrared (NIR) dual-band persistent luminescence after irradiation by 254 nm ultraviolet (UV) light. UVB and NIR afterglow are ascribed to the distinct Bi 3+ and Bi 2+ emitters, respectively, proven by comprehensive spectroscopic investigations including X-ray absorption near-edge structure spectra and X-ray photoelectron spectroscopy. Besides, this phosphor also exhibits exceptional photochromic features, accompanied by a rapid body color transformation from white to brown in response to 254 nm UV light within 60 s and excellent recovery capacity upon thermal or blue/white light stimulation. The combination of UVB persistent luminescence of Bi 3+ and NIR afterglow of Bi 2+ coupled with reversible white-to-brown photochromism phenomenon offers one type of promising multifunctional luminescence material, showing potential to be used for optical storage and anti-counterfeiting applications.