A multicolor‐emitted phosphor for temperature sensing and multimode dynamic anti‐counterfeiting

Abstract

The charge carrier capture phosphors for multifunctional integrated applications are gaining popularity these days. The realization of multiple optical properties often requires complex modulation processes, such as multiple ions doping and matrix substitution. Herein, we designed a single-doped Ba 0.99 Ga 2 O 4 :0.01Bi phosphor with two emission peaks of 500 and 610 nm, both of which have different responses when changing temperatures (298-473 K). Theoretical calculations combined with experimental studies imply that the dopant Bi 3+ ions occupy regular Ba sites and the vacancy-surrounded Ba sites, which act as luminescence centers. Meanwhile, doping-induced 𝑉 ′′′ Ga and Bi ⋅ Ba defects can operate as traps to store carriers that could be released and migrate toward specific luminescent centers under thermal disturbance. This phosphor shows excellent absolute sensitivity toward optical temperature sensing (S a = 3.4% K −1 ). We also offered a quadruple anti-counterfeiting application show based on the multicolor emission behavior of Ba 0.99 Ga 2 O 4 :0.01Bi with photostimulated luminescence at room temperature, different photoluminescent colors at room and high temperatures, as well as afterglow colors from yellow to green. This work stimulates the exploration of modulating the luminescence centers and trap levels to construct multifunctional fluorescent materials.

Gradient defects mediate negative thermal quenching in phosphors

“…Luminescent materials show wide-ranging application prospects in light-emitting devices, [1][2][3][4] anti-counterfeiting, 5,6 biological imaging, 7,8 and optical information storage. 9 However, the emission intensity of most luminescent materials is evidently reduced under the temperature range of 373 to 473 K compared to the initial state, which greatly limits their applications under high temperatures up to 473 K. The emission loss with increasing temperature is known as the thermal quenching (TQ) effect, [10][11][12] one of the greatest obstacles to extend the commercial applications of existing materials. [13][14][15] The TQ results in significant increase of non-radiation distribution of excited state electrons of luminescent ions.…”

Bismuth‐Activated Persistent Phosphors

“…The design of Bi-activated PersL materials is Reproduced with permission. [98] Copyright 2022, The American Ceramic Society.…”

“…Recently, our team reported a multicolor‐emitting phosphor Ba 0.99 Ga 2 O 4 :0.01Bi 3+ , which could be applied in dynamic anti‐counterfeiting. [ 98 ] The realization of multiple anti‐counterfeiting modes is attributed to the different emission centers of Bi ions and the presence of Ga vacancies. Figure a shows that the photoluminescence color of the Ba 0.99 Ga 2 O 4 :0.01Bi 3+ turns from yellow at room temperature to orange at high temperatures.…”

“…c) Conceptual diagram for scanning a code prepared by Ba 0.99 Ga 2 O 4 :0.01Bi 3+ to decoding the information. Reproduced with permission [98]. Copyright 2022, The American Ceramic Society.…”

Anti‐Counterfeiting Application of Persistent Luminescence Materials and Its Research Progress

“…successfully prepared a novel material with abundant trap energy levels by selectively doping Bi 3+ into the MgGa 2 O 4 matrix (MgGa 2 O 4 :Bi 3+ ). [ 114 ] Due to the high defect density of Bi doping, multiple trap levels with continuous distribution exist in MgGa 2 O 4 :Bi 3+ , where deep traps are essential for information storage. Different luminance information is demonstrated at room temperature and at high temperature of 200°C as depicted in Figure 6c, which directly demonstrates the optical information reading and writing capability of the material.…”