A Novel Oxygen Vacancy in ScPO4:Er for Luminescence Anti‐Thermal Quenching

Abstract Different from previously reported shallow defects in ScPO 4 , herein we have uncovered a deep defect, oxygen vacancy ( V O ). The perfect energy level match with 4 S 3/2 / 4 F 9/2 in doped Er 3+ allows V O to accept and store the excitation energy transferred from Er 3+ , which is then released and back‐transferred to Er 3+ upon heating, and finally leads to significant luminescence anti‐thermal quenching (LATQ). Moreover, the concentration of V O can be adjusted by simple atmospheric annealing, which allows modulation of V O → Er 3+ energy transfer for adjustable LATQ in ScPO 4 :Er, i.e., downshifting LATQ up to 843 K and upconversion LATQ till a record‐high temperature of 1323 K, and thus unparalleled performance of the classic compound ScPO 4 :Er in thermophotovoltaics (TPV) and dual‐mode luminescence thermometers.