應用於短波紅外線發光二極體之高效鉺摻雜尖晶石螢光粉

Abstract

短波紅外線(shortwave infrared; 1000–1700 nm)區段因其波長範圍與現今高靈敏度InGaAs 成像偵測器相匹配，近年已於非破壞性產品檢測、生醫影像、安全等領域中嶄露頭角。發光二極體則因其具低功耗、高穩定性、體積小、波長可調性等優勢，故成為目前應用於螢光粉材料之主流光源。故開發具高量子效率且可應用於商業藍光發光二極體之短波紅外光螢光粉轉換材料，為本研究之主要核心目標。 本研究第一部分致力於探討 Cr3+與Er3+共摻雜部分反尖晶石結構之MgGa2O4螢光粉，將分析Cr3+與Er3+兩者發光中心間能量轉移行為。當此主體結構摻雜高濃度Cr3+時，將促使Cr3+形成離子對及離子團簇，進而生成多樣化之Cr3+放光能階與寬譜放光性質，同時兼具高量子效率於近紅外光一區。隨後進一步引入具短波紅外線放光能力之Er3+，雖其發光受限於嚴謹之Laporte 禁制躍遷，導致吸收截面狹窄與低放光效率，然藉Cr3+團簇所形成之多重能量轉移路徑，可有效補償Er3+固有之低吸收截面缺點，顯著提升近紅外放光效率。 本研究之第二部分則聚焦於 Cr3+、Ni2+及Er3+之多摻雜MgGa2O4 螢光粉系統，將進一步引入第二種具短波紅外線放光能力之Ni2+離子，使第一部分研究殘餘之Cr3+放光能量有效轉移至短波紅外線區段，實現全域寬譜放光特性。Ni2+之摻雜將調控系統內部能量轉移路徑，重新建立整體放光表現，可生成寬譜且高量子效率之短波紅外線放光，展現獨特之應用潛力。 本研究之新穎性除系統性研究螢光粉之結構性質、放光性質及探討活化劑間複雜能量轉移行為外，亦將兩研究之短波紅外線螢光粉封裝於發光二極體中，藉比較具高強度窄譜放光與強度均勻化之寬譜放光螢光粉特性，於實際應用中展現彼此差異性，實現應用為導向之短波紅外線螢光粉之設計策略，為未來開發短波紅外線轉換材料提供潛在之應用實例與研究方向。

The shortwave infrared (SWIR, 1000–1700 nm) region has attracted considerable attention due to its excellent compatibility with high-sensitivity InGaAs detectors, demonstrating great potential for non-destructive testing, biomedical imaging, and security applications. Light-emitting diodes (LEDs), featuring low power consumption, high stability, compact size, and wavelength tunability, are widely used as excitation sources for phosphor-converted materials. Therefore, developing high-performance SWIR phosphors applicable to LED integration is the primary goal of this study. In the first part, Cr3+ and Er3+ co-doped partially inverse spinel MgGa2O4 phosphors are investigated. High-concentration Cr3+ doping leads to forming Cr3+ ion pairs and clusters, resulting in diversified energy levels and broad emissions ranging from 700 to 1100 nm, with high efficiency in the first near-infrared region. Er3+ ions are further introduced, though low absorption cross-sections inherently limit their luminescence due to Laporte-forbidden transitions. However, the Cr3+ clusters offer multiple energy transfer pathways, effectively compensating for the weak absorptionof Er3+ and significantly enhancing its emission efficiency. In the second part, Ni2+ ions are introduced to further transfer the residual Cr3+ emission energy into the SWIR region, achieving broadband, full-spectrum emission. Ni2+ doping modulates internal energy transfer routes and results in intensity-balanced broadband emission, demonstrating potential for advanced applications. The novelty of this study lies not only in systematically analyzing the structural and luminescent properties and energy transfer mechanisms but also in demonstrating LED devices based on two phosphors with distinct emission characteristics, achieving an application-driven SWIR phosphor design strategy.