Abstract: Photothermal therapy (PTT) provides a new approach for the treatment of tumors and bacterial infections. It relies on photothermal agents (PTAs) to absorb near-infrared light, dissipate the non-radiative energy generated by photoexcitation to the lesion site, and achieve thermal ablation of local tissues. However, the development of organic PTAs with both efficient photothermal conversion and precise targeting functions is challenging.This paper focuses on the molecular engineering optimization of heptamethine cyanine (Cy7) dye molecules, and proposes a strategy of aggregate state regulation and synergistic enhancement of functional groups. A novel cationic derivative Cy7T-TPP is constructed by introducing triphenylphosphine cation (TPP⁺) into the neutral cyanine skeleton. This derivative has three advantages: TPP⁺ endows it with bacterial membrane anchoring and mitochondrial targeting capabilities; it induces H-aggregates to enhance the close stacking between molecules, with a photothermal conversion efficiency of 51.65%; TPP⁺ shields against reactive oxygen species attack and improves stability. Experiments have confirmed that Cy7T-TPP has excellent anti-tumor and antibacterial efficacy, providing a new molecular engineering paradigm for the development of highly stable and targeted organic photothermal materials.