Efficient and Stable Short-Wave Infrared-Emitting from Partly Inverse Spinel ZnGa2O4: Fe3+, Ni2+ for Versatile Applications: Self-Photoluminescence, Anion Substitution, and Energy Transfer Study

Abstract

NIR phosphors based on commercial LED pumping are gained great concerns. However, blue excitation and lack of broadband NIR phosphors are still obstacles. Herein, NIR-II emitting ZnGa₂O₄: Fe³⁺, Ni²⁺ with autologous defects are designed. Self-PL is associated with intrinsic defects including [GaO₆], antisite defects ($G{a}_{Zn}^{·}$) and oxygen defects (O_i). Based on efficient energy transfer, ZGO: Fe³⁺, Ni²⁺ exhibits broadband NIR-II emission. To improve PL efficiency of Fe³⁺, an oxygen defects repairing engineering via anionic F⁻-substitution artifice is executed, resulting in high PL quantum efficiency of ≈64.6% and splendid thermal stability (≈75.5%@423K) for ZGOF: Fe³⁺, Ni²⁺. The reduction in local site symmetry after F-substitution splits energy states of Fe³⁺ in purely octahedral crystal field also helps to relief the Laporte selection rule and widens excitation/PL spectra with high efficiency. A NIR-II phosphor-converted LED (pc-LED) by combination of ZGOF: Fe³⁺, Ni²⁺ and a nUV LED chip via remote ʻcappingʼ packaging strategy with high radiant power is fabricated and its versatile applications in night vision, non-destructive detection, food analysis and optical pressure sensing are demonstrated. This study paves a feasible way to realize high-quality NIR phosphor and its corresponding device for wide applications.