Multimodal Luminescence in Antimony(III)-Doped Hybrid Manganese(II)-Based Compounds for Dynamic Anticounterfeiting Encryption and Optical Thermometry

The synergistic interaction between Mn²⁺ and Sb³⁺ ions in organic–inorganic hybrid single crystals has unlocked exciting optical applications for multiple band emission centers. Here, (TPMP)₂MnBr₄:Sb³⁺ single crystals were synthesized. They exhibited energy transfer from Mn²⁺ to Sb³⁺ ions, producing color-tunable luminescence and multiband emission. The dual emission leveraged d-d transitions in Mn²⁺ for green emission and self-trapped excitons in Sb³⁺ for broad red emission. Precise control of the excitation energy created broad color gamut modulation on the CIE chromaticity diagram, ranging across green, yellow, and red. Furthermore, there were distinct temperature sensitivities of the Mn²⁺ and Sb³⁺ emission centers, leading to robust fluorescence intensity ratios for temperature sensing with high relative sensitivity (3.92% K^–1) and absolute sensitivity (5.42% K^–1). These results indicated significant (TPMP)₂MnBr₄:Sb³⁺ potential for optical temperature sensing and dynamic information for anticounterfeiting encryption. This work provides a pathway for energy-transfer dynamics and luminescence applications of Mn²⁺-Sb³⁺ systems.