A red-light-chargeable near infrared MgGeO3:Mn2+,Yb3+ persistent phosphor for bioimaging and optical information storage applications

Near-infrared (NIR) persistent phosphors have attracted extensive research interest owing to their distinct wavelength features and self-sustained luminescence properties. However, the high-energy ultraviolet light that is consistently used to charge these phosphors has compromised some promising applications, especially for biomedical imaging. Herein, we have successfully utilized long-wavelength 635 nm red-light to achieve intense NIR persistent luminescence in a MgGeO3:Mn2+,Yb3+ phosphor. Seconds to minutes of 635 nm red-light charging can result in long-lasting NIR afterglow at around 680 nm for longer than 12 h. The photon trapping and detrapping processes in the MgGeO3:Mn2+,Yb3+ phosphor were investigated in detail by varying the 635 nm red laser output power and the excitation duration, which indicate that a two-photon upconversion charging process is responsible for NIR persistent luminescence upon red-light illumination. The red-light-charging capability and self-sustained NIR luminescence properties make this material perfectly suited to applications across a wide number of fields, such as acting as ideal optical probes for deep-tissue bio-imaging and developing optical data storage technology for information security systems.