Shao Yan,Yanjie Liang,Yi Zhang,Bibo Lou,Jingwei Liu,Dongxun Chen,Shihai Miao,Chonggeng Ma
Solar-blind ultraviolet-C (UVC; 200–280 nm) luminescent materials have exhibited great potential for wide applications in photomedicine and photochemistry due to the unique spectral features of UVC light. However, it is still a challenging work to develop persistent phosphors emitting in the UVC spectral region owing to the lack of suitable host materials and emitting centers. Herein, we report a series of LiLuSiO4:Pr3+,Sm3+ UVC persistent phosphors that can be charged by a 254 nm UV lamp or a high-energy X-ray beam giving rise to long-lasting UVC light emission peaking at 280 nm. More importantly, a considerable enhancement of UVC afterglow intensity and decay time has been achieved by Sm3+ co-doping because the Sm3+ ions can act as effective electron traps, which has been verified by the spectroscopic investigations and first-principles calculations. On top of this, narrowband ultraviolet-B (NB-UVB) persistent luminescence with a line emission at 313 nm has also been realized by introducing Gd3+ into LiLuSiO4:Pr3+,Sm3+ persistent phosphors based on persistent energy transfer from Pr3+ to Gd3+. Considering that the UVC and NB-UVB persistent luminescence can fully avoid severe interference from ambient light, the as-prepared LiLuSiO4:Pr3+,Sm3+ and Li(Lu,Gd)SiO4:Pr3+,Sm3+ persistent phosphors can find promising applications as invisible identification taggants in a bright environment.
Yi Zhang,Shao Yan,Fang Xiao,Xihui Shan,Xulong Lv,Weili Wang,Yanjie Liang
With the occurrence of global health events such as COVID-19, the development of high-performance ultraviolet-C (UVC) light sources for efficient and convenient sterilization applications holds promising scientific and engineering prospects. However, discovering reliable and stable luminescent materials capable of converting incident excitation energy to UVC radiation remains a challenge. Herein, we report a new Sr2P2O7:Pr3+ phosphor that exhibits exceptional capabilities in X-ray energy absorption, storage, UVC-light conversion, and persistent UVC light emission. Specifically, minutes of X-ray excitation can result in more than 24 h of continuous UVC persistent luminescence when monitored at 222 nm emission, realizing far-UVC afterglow for the first time. Intense UVC persistent light emission could be detected by a UVC corona camera in bright indoor and outdoor environments without interference from artificial light or natural sunlight, in consideration of the avoidance of the spectral overlap with ambient light. The self-sustained UVC persistent luminescence form was demonstrated as an optical-conversion strategy for sterilization application, whereby the charged Sr2P2O7:Pr3+ persistent phosphor could effectively inactivate infectious methicillin-resistant Staphylococcus aureus (MRSA) within 30 min in an excitation-free manner, offering new insights into developing UVC light sources for sterilization applications. This work expands the field of UV persistent luminescence research to the far-UVC spectral region and is expected to bring new and power-free solutions to some important applications where far-UVC light is needed, such as sterilization and photodynamic therapy.
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