Abnormal Bi³⁺-Activated NIR Emission in Highly Symmetric XAl₁₂O₁₉ (X = Ba, Sr, Ca) by Selective Sites Occupation

Abstract

Near-infrared light-emitting diodes (NIR-LEDs) are potential candidates in food composition analysis, temperature and security monitoring, biometrics, and medical applications. To realize the above objectives, the development of NIR-emitting phosphors is urgently required. Herein, a novel NIR emission is successfully achieved in Bi3+-activated XAl12O19 (X = Ba, Sr, Ca) compounds by constructing the selective site occupation of Bi3+ in Al3+ polyhedra with small coordination number. The designed phosphors exhibit broad-band NIR emission of Bi3+ from 600 to 1000 nm. Interestingly, a broad photoluminescence control from blue to red is also achieved by just changing the sintering atmosphere. The blue emission of Bi3+ should be assigned to the prior occupation in X2+ sites and the existence of oxygen vacancy. This work not only provides a novel insight to develop NIR-emitting Bi3+-activated phosphors but also helps to reveal the underlying NIR luminescence mechanism of Bi3+ in inorganic compounds.

Li/Na substitution and Yb3+ co-doping enabling tunable near-infrared emission in LiIn2SbO6:Cr3+ phosphors for light-emitting diodes

“…Since the optical performance of NIR pc-LEDs mainly depends on the phosphors used, intensive efforts have been made to exploit broadband NIR phosphors via rare-earth ion- (Eu 2+ ), transition metal ion- (Cr 3+ , Ni 2+ , Mn 2+ , Fe 3+ ), or Bi ion (Bi + , Bi 3+ )-activated inorganic matrices ( Tang et al., 2020 ; Gao et al., 2020 ; Song et al., 2019 ; Wei et al., 2020 ; Guan et al., 2020 ). Unfortunately, single invisible fluorescence emissions of Eu 2+ , Mn 2+ , and Fe 3+ ions are hard to acquire, and their emissions FWHM are insufficient ( Berezovskaya et al., 2013 ; Song et al., 2015 ; Zhou et al., 2020 ).…”

Recent Advances in Super Broad Infrared Luminescence Bismuth-Doped Crystals

“…As of today, it is a general consensus that tri-or higher-valence Bi ions are not the origin of NIR emission, as agreed with that in glass (Peng et al, 2011). However, the NIR emissions of Bi 3+ have recently been confirmed by designing Bi 3+ in XAl 12 O 19 (Wei et al, 2020.). Finally, the decay times vary from several to several hundreds of microsecond (ms).…”

Giant Red‐Shifted Emission in (Sr,Ba)Y2O4:Eu2+ Phosphor Toward Broadband Near‐Infrared Luminescence

“…Dorenbos has studied the ε CFS of Ce 3+ in oxides, and the optical properties of Ce 3+ and Eu 2+ show similarity. [16] Therefore, the ε CFS value for describing the characteristic of Ce 3+ can also be applied to Eu 2+ by the following equations: [2,9,16]…”

“…Broadband near-infrared (NIR) light sources have attracted enormous attention owing to the applications in medical diagnosis, food analysis, health monitoring, bio-sensing, agriculture, and so on. [1] Traditional solidstate NIR light-emitting devices, such as halogen lamps, laser diodes, and supercontinuum lasers, suffer severely from large sizes, high electrical consumption, low efficiency, and short usage lifetime, [2] which hinder their broader applications. Recently, NIR phosphor-converted light-emitting diodes (NIR pc-LEDs) have emerged as a feasible strategy to meet the requirements due to their diminutive size, low energy consumption, high output power, and long lifetime.…”