Abstract: Photothermal therapy (PTT) uses photothermal agents (PTAs) to absorb near-infrared light and dissipate the non radiative energy generated by light excitation to the lesion site, achieving local tissue thermal ablation and providing a new approach for treating tumors and bacterial infections. However, developing organic PTAs that combine efficient photothermal conversion and precise targeting functions faces challenges. This article focuses on the molecular engineering optimization of heptamethylene cyanine dye, proposing a strategy of aggregation state regulation and synergistic strengthening of functional groups. A novel cationic derivative Cy7T-TPP is constructed by introducing triphenylphosphine cation (TPP⁺) into the neutral cyanine skeleton. It has three advantages: TPP ⁺ endows bacteria with membrane anchoring and mitochondrial targeting abilities; Inducing H-aggregates to enhance tight intermolecular stacking, achieving a photothermal conversion efficiency of 51.65%; TPP shields against reactive oxygen species attacks and enhances stability. Experimental results have confirmed its excellent anti-tumor and antibacterial efficacy, providing a new paradigm of molecular engineering for the development of highly stable and targeted organic photothermal materials.