應用於近紅外光二區至三區之螢光玻璃材料

Abstract

近紅外光(near-infrared; NIR)材料具低散射、高穿透深度及特定生物視窗之優勢，近年被廣泛應用，故NIR-II(1000–1700 nm)與NIR-III(1700–2500 nm)波段逐漸成為高解析與深層成像之重要研究方向。長波長近紅外放光常受熱活化非輻射躍遷影響，導致溫度升高時發光強度快速衰減與熱淬滅現象，使整體量子效率與熱穩定性普遍偏低，故開發具高效率與熱穩定之近紅外螢光粉材料為關鍵研究。本論文藉玻璃嵌入螢光粉(glass-in-phosphor; GiP)複合設計策略，系統性探討不同活化劑能量轉移機制與結構工程於紅外放光效能之影響。 本研究之第一部分聚焦於部分反尖晶石MgGa2O4主體中摻雜Cr3+與Ni2+之近紅外二區螢光粉系統，利用Cr3+團簇形成能量轉移為研究核心，進一步引入Ni2+，藉能階匹配將Cr3+團簇之發光能量轉移至更長波段，拓展整體放光範圍。同時，結合3CaO–Ga2O3–3GeO2玻璃形成GiP複合結構後，可有效提升熱穩定性與高功率激發下之放光穩定度，實現兼具寬譜與結構穩定之放光特性。 第二部分則聚焦於Y2GeO5結構中Tm3+與Ho3+共摻雜之近紅外三區螢光粉系統。藉兩者稀土離子能量轉移過程強化長波段之近紅外放光表現，並進一步導入GiP結構以降低非輻射躍遷機率與晶格振動影響，最終提升熱穩定性與整體放光效率，此設計策略可突破1700 nm以上區段量子效率與熱穩定性不佳之限制。 本研究之新穎性於建構兩套GiP紅外螢光粉系統，分別實現寬頻NIR-II放光與延伸至NIR-III波段之長波紅外光系統，並由晶體結構調控、活化劑能量轉移機制、複合材料等面向進行系統性探討。研究成果建立於主體與活化劑設計之關聯性，並揭示提升紅外放光熱穩定性之玻璃複合策略，將為未來高效率長波紅外螢光轉換材料之開發提供明確方向與實用基礎。

Near-infrared (NIR) materials are attractive for deep-tissue imaging due to low scattering and high penetration, particularly in the NIR-II (1000–1700 nm) and NIR-III (1700–2500 nm) regions. However, long-wavelength emission is subject to thermally activated nonradiative relaxation, resulting in low quantum efficiency and poor stability. This dissertation employs a Glass-in-Phosphor (GiP) strategy to enhance near-infrared luminescence via activator energy transfer and structural engineering. The first part of this study investigates NIR-II phosphors based on the partially inverse-spinel MgGa2O4 doped with Cr3+ and Ni2+, with an emphasis on Cr3+ cluster formation and related energy-transfer processes. Energy-level matching Ni2+ enables partial transfer of emission energy from Cr3+ clusters to longer wavelengths, broadening the emission range. Incorporating a 3CaO–Ga2O3–3GeO2 glass phase into a GiP composite further enhances thermal stability and emission robustness under high-power excitation. The second part focuses on NIR-III phosphors based on Y2GeO5 co-doped with Tm3+ and Ho3+. Rare-earth energy transfer regulates excited-state population and strengthens long-wavelength emission. The GiP suppresses nonradiative relaxation and lattice-vibration effects, improving thermal stability and emission efficiency beyond 1700 nm. The novelty of this work lies in the construction of two GiP-based infrared phosphor systems that achieve broadband NIR-II and extended NIR-III emission. By correlating crystal structure with activator energy transfer, this study proposes a glass-composite strategy to enhance thermal stability and guide the development of high-efficiency long-wavelength infrared phosphors.