Tunable Multicolor in Heterojunction Ln(BTB) Fast Prepared by Liquid Plasma with In Situ Spectral Monitoring for Anticounterfeiting Application

Lanthanide metal–organic frameworks (Ln-MOFs) represent a promising class of multicolor luminescence nanomaterials with broad application prospects. However, the fabrication of high-quality, tunable multicolor Ln-MOFs for optical applications remains highly challenging due to the lack of suitable processing methods. In this work, an integrated device was introduced that used dielectric barrier discharge (DBD) liquid plasma for synthesis, which was coupled with in situ spectral monitoring, enabling the fabrication of multicolor heterojunction Ln-MOFs. This approach facilitates precise multicolor control from red, orange-red, yellow, and pale-green to green by adjusting the Tb 3+ -to-Eu 3+ ratio based on real-time spectral data. The heterojunction architecture effectively suppresses undesired direct Tb 3+ -to-Eu 3+ energy transfer, which commonly occurs in mixed-metal structures. The fabricated heterojunction Ln-MOFs were characterized by using X-ray diffraction, infrared spectroscopy, UV–vis spectroscopy, scanning electron microscopy, and photoluminescence techniques. The application studies demonstrated that these multicolor heterojunction Ln-MOFs hold significant promise for the development of anticounterfeiting materials across a wide range of applications.