Strategies on boosting photothermal conversion efficiency of organic molecules for photothermal therapy

As a novel phototherapeutic modality with non-invasiveness, high spatiotemporal resolution, and minimal side effects, photothermal therapy (PTT) has garnered considerable attention in recent years. Diverse photothermal nanoagents (PTNAs) have been developed and substantial achievements have been made in the PTT area, enabling their great clinical potential. Among the PTNAs, organic PTNAs (OPTNAs) based on organic molecules are more desirable compared to their inorganic counterparts due to their inherent biocompatibility and easily tailored optical properties. While several reviews have discussed strategies to enhance photothermal conversion efficiency (PTCE) in organic systems, most have focused primarily on conventional dye-based mechanisms and fundamental photophysics. In comparison, this review highlights the latest molecular-level innovations that integrate optical, structural, and supramolecular engineering to enhance PTCE. We particularly highlight cutting-edge approaches, such as molecular packing modulation, self-assembly-induced crystallization, compressional wave energy dissipation, and cocrystal engineering strategies that have emerged only in recent years and were not previously covered in reviews. Furthermore, this review connects these photothermal strategies with practical design principles for next-generation organic photothermal agents suitable for clinical translation. We anticipate that this contribution will provide readers with valuable information on constructing OPTNAs with elevated PTCE and guide the design and preparation of such high-performance OPTNAs in the future.