Near-infrared long persistent luminescence of Er3+ in garnet for the third bio-imaging window

Abstract

By utilizing efficient persistent energy transfer from Ce³⁺ to Er³⁺, we have successfully developed a novel garnet persistent phosphor of Y₃Al₂Ga₃O₁₂ doped with Er³⁺, Ce³⁺, Cr³⁺ ions (YAGG:Er–Ce–Cr) exhibiting long (>10 h) near-infrared (NIR) persistent luminescence (PersL) in the broad range from 1450 nm to 1670 nm due to the typical Er³⁺:⁴I_13/2 → ⁴I_15/2 transition in garnet. The NIR PersL bands of Er³⁺ match well with the third bio-imaging window (NIR-III, approximately from 1500 nm to 1800 nm) and the response curve of InGaAs detectors. The photon emission rate (8.33 × 10¹⁷ cps Sr⁻¹ m⁻²) of the YAGG:Er–Ce–Cr persistent phosphor at 10 min after ceasing blue light illumination was over two times higher than that of the widely used ZnGa₂O₄:Cr³⁺ deep-red persistent phosphor (3.30 × 10¹⁷ cps Sr⁻¹ m⁻²). We also show the first PersL imaging by a commercial InGaAs camera monitoring Er³⁺ emission indicating that this material can be a promising candidate for in vivo bio-imaging in the NIR-III window.