Electron Tunneling Charging upon Sunlight for Near‐Infrared Persistent Luminescence

Abstract

For the conventional persistent luminescence (PersL) charging processes, carriers are photo-pumped to the conduction band (CB) or high-energy excited states (HES) under short-wavelength UV or coherent near-infrared (NIR) laser excitation. Herein, electron tunneling charging behavior is reported in Cr 3+ , Sm 3+ co-doped NIR PersL magnetoplumbite SrGa 12 O 19 , which allows for efficient charging by incoherent visible light. First, the electrons are efficiently captured by the neighboring Ga II -O 2− electron-hole trap centers via a tunneling process, and then these excited electrons are transferred to shallow traps via a persistently energetic optical pump. This work further optimizes the PersL performance via engineering the energy band through partial substitution of In 3+ for Ga 3+ . Consequently, tunneling charging occurring near the neighboring Cr 3+ -traps dimers enables Sr(Ga,In) 12 O 19 :Cr 3+ ,Sm 3+ to display brighter NIR PersL (≈760 nm, peak; ≈100 nm, FWHM) than gallate spinel under sunlight irradiation. This work provides insights into electron tunneling charging under low-energy excitation for NIR PersL, which may inspire more PersL explorations for practical applications.

Simultaneous NIR photoluminescence and mechanoluminescence from Cr3+ activated MgGa2O4 phosphors with multifunctions for optical sensing

“…They can capture light signals passing through biological tissues, indicating potential for developing narrowband ML materials for the NIR I region. 20 Also, Cr 3+ is efficiently excitable by blue light. Using blue LED chips with Cr 3+ doped near-infrared phosphors can notably boost near-infrared emission efficiency.…”

Narrowband Ultraviolet-B Persistent Luminescence in an Indoor-Lighting Environment through Energy Transfer from Host Excitons to Gd3+ Emitters in ScPO4

“…Persistent luminescence (PersL) is a special optical phenomenon, characterized by a self-luminescing feature for an extended time from minutes to hours after the cessation of external excitation [usually X-ray, ultraviolet (UV), or short-wavelength visible light]. , In the past decades, substantial attention has been given to persistent phosphors for their important applications in emergency signage, traffic signs, luminous paints, and medical diagnostics. − Till now, the emission wavelengths of the developed long persistent phosphors are mainly located in the visible and near-infrared (NIR, 700–900 nm) spectral regions. − Among them, the blue CaAl 2 O 4 :Eu 2+ ,Nd 3+ and the green SrAl 2 O 4 :Eu 2+ ,Dy 3+ phosphors have gained commercial success as glow-in-the-dark indicators, considering their high initial afterglow intensities and sufficiently long duration time in a dark or low light environment . Moreover, a series of Cr 3+ -doped gallate-based NIR afterglow materials, such as Zn 3 Ga 2 Ge 2 O 10 :Cr 3+ , LiGa 5 O 8 :Cr 3+ , ZnGa 2 O 4 :Cr 3+ , and Sr­(Ga,Al) 12 O 19 :Cr 3+ , , have also been discovered and developed recently, which exhibit intense NIR emission peaking at ∼700 nm with a very long afterglow of up to several hundreds of hours. These Cr 3+ -doped nano-gallates have been quickly proven to be excellent optical probes for in vivo biomedical imaging applications. ,, …”

“…8−11 Among them, the blue CaAl 2 O 4 :Eu 2+ ,Nd 3+ and the green SrAl 2 O 4 :Eu 2+ ,Dy 3+ phosphors have gained commercial success as glow-in-thedark indicators, considering their high initial afterglow intensities and sufficiently long duration time in a dark or low light environment. 12 Moreover, a series of Cr 3+ -doped gallate-based NIR afterglow materials, such as Zn 3 Ga 2 Ge 2 O 10 :Cr 3+ , 8 LiGa 5 O 8 :Cr 3+ , 13 ZnGa 2 O 4 :Cr 3+ , 14 and Sr(Ga,Al) 12 O 19 :Cr 3+ , 15,16 have also been discovered and developed recently, which exhibit intense NIR emission peaking at ∼700 nm with a very long afterglow of up to several hundreds of hours. These Cr 3+ -doped nano-gallates have been quickly proven to be excellent optical probes for in vivo biomedical imaging applications.…”

Sunlight-activated Eu3+-doped CaNaSb2O6F yellow-orange long-persistence luminescence material

“…Even the most famous red PersL phosphor, Y 2 O 2 S:Eu 3+ ,Ti 4+ ,Mg 2+ , still cannot fully meet the needs of practical application due to its high cost and low sensitivity to room light. [13][14][15][16][17][18][19] Thus, it is an ongoing challenge to develop efficient sunlight-activated warm-color persistent luminescence phosphors to fulfill the high demands for a variety of practical applications.…”