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

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+:4I13/2 → 4I15/2 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.

通过利用从Ce³⁺到Er³⁺的高效持久能量传递，我们成功开发了一种新型的掺杂Er³⁺、Ce³⁺、Cr³⁺离子的钇铝镓石榴石持久荧光粉（YAGG:Er - Ce - Cr），由于石榴石中典型的Er³⁺:⁴I₁₃/₂ → ⁴I₁₅/₂跃迁，其在1450 nm至1670 nm的宽范围内呈现出长时间（>10小时）的近红外（NIR）持久发光（PersL）。Er³⁺的近红外持久发光带与第三生物成像窗口（近红外 - III，约1500 nm至1800 nm）以及InGaAs探测器的响应曲线匹配良好。在停止蓝光照射10分钟后，YAGG:Er - Ce - Cr持久荧光粉的光子发射率（8.33×10¹⁷ cps Sr⁻¹ m⁻²）比广泛使用的ZnGa₂O₄:Cr³⁺深红色持久荧光粉（3.30×10¹⁷ cps Sr⁻¹ m⁻²）高出两倍多。我们还通过商业InGaAs相机监测Er³⁺发射展示了首次持久发光成像，这表明该材料在近红外 - III窗口的体内生物成像方面可能是一种有前途的候选材料。