Interface Defect and Spatial Charge Transfer Contribute to the Dynamic Anticounterfeiting and Fingerprint Recognition Applications and Mechanism Insights of A/B Site–Doped BaMoO 4 Phosphors

ABSTRACT The Ba 1− x Ca x MoO 4 and BaMo 1− x W x O 4 ( x = 0.5–0.9) phosphors were synthesized by the polyacrylamide gel method. The introduction of Ca ion into BaMoO 4 formed a type I heterojunction between BaMoO 4 and CaMoO 4 , while W ion was added to BaMoO 4 formed a single phase of BaMo 1− x W x O 4 . The interaction between interfaces and defects causes a reduction in the band gap ( E g ) value of the Ba 1− x Ca x MoO 4 phosphor and an increase in the E g value of the BaMo 1− x W x O 4 phosphor due to the Burstein–Moss effect compared to BaMoO 4 . The orange‐red fluorescence peaks at 638 and 680 nm were detected in Ba 1− x Ca x MoO 4 due to the formation of a type I band arrangement heterojunction, as well as the defects at the interface, as a result of a 530‐nm excitation wavelength. The difference is that when excited by a wavelength of 256 nm, the BaMo 1− x W x O 4 phosphor emits purple and blue light emission peaks at 378 and 424 nm, respectively. The 1 T 2 → 1 A 1 transition in MoO 4 2− and WO 4 2− leads to the blue‐violet luminescence of the BaMo 1− x W x O 4 phosphor. These phosphors have been found to be suitable for dynamic anticounterfeiting and fingerprint recognition applications due to their special interface defect and spatial charge transfer.