Magnetic-Responsive Near-Infrared Photothermal Conversion and Imaging in Organic Charge Transfer Cocrystals
Organic charge-transfer cocrystals comprising a triphenylene donor and F4TCNQ acceptor (Tri-F4TCNQ) were synthesized and characterized for magnetic-responsive near-infrared photothermal conversion and imaging. The cocrystal exhibits broad absorption from 300 to 1800 nm, with a photothermal conversion efficiency (PCE) of 63.6% under 1064 nm laser excitation. This high efficiency is attributed to dominant nonradiative decay pathways and suppressed radiative channels. The material displays intrinsic magnetism, and an external magnetic field enhances photothermal conversion by increasing the spin-parallel state ratio, thereby boosting nonradiative recombination. Photothermal imaging shows a corresponding magnetic field response. Structural stability was confirmed by differential scanning calorimetry, thermogravimetry, and X-ray diffraction, with negligible degradation after six months in air. The cocrystal also demonstrates photosensitivity and magnetic field responsiveness, enabling applications in rapid content extraction and information encryption. This work represents a rare integration of magnetism and photothermal conversion in a single organic cocrystal, offering a foundation for advanced photothermal imaging and magnetic manipulation technologies.