Persistent luminescence (PersL) is an extraordinary optical phenomenon defined by the prolonged emission of light lasting from several seconds to hours following the removal of excitation sources. At present, afterglow materials are extensively utilized in security signage, anti-counterfeiting measures, information storage, bioimaging, and nocturnal vision applications due to their long-lasting luminescence after excitation. In comparison to traditional visible afterglow, near-infrared (NIR) PersL provides enhanced tissue penetration, reduced background noise, and superior biocompatibility, rendering it particularly advantageous for biomedical and security purposes. Moreover, since NIR light remains undetectable to the human eye in low-light conditions, such materials facilitate critical nocturnal monitoring activities, including aerial drone detection, vehicular tracking on highways, and surveillance of moving pedestrians. Although advancements have been made in steady-state NIR luminescence, the development of materials exhibiting tunable NIR afterglow and dynamically adjustable emission properties continues to pose significant challenges.

This study introduces a series of NIR PersL solid solutions achieved through the modification of the chemical composition via unit cosubstitution, which enables the modulation of emission characteristics in the deep-red and NIR spectral ranges. These solid solutions were systematically analyzed to clarify the relationship between their structural attributes and luminescent behaviors, as well as to investigate the variations in trap distribution and density induced by compositional changes. This research evaluates the advantages and limitations of chemical unit cosubstitution in the enhancement of NIR persistent phosphors, thereby encouraging further investigation into luminescent materials with unique properties.