An Organic High-Temperature Photothermal Material for Solar Conversion and Storage

Photothermal conversion, the most direct pathway for solar utilization, has garnered widespread attention and made great advances. In recent years, organic high-temperature photothermal materials have demonstrated significant application potential for their properties of substantially surpass the temperature limits of conventional organic photothermal systems. However, their molecular design principles, structure-property relationships, and photothermal conversion mechanisms are still unclear, with the high-temperature photothermal behavior lacking quantitative interpretation. Here we report an organic high-temperature photothermal material (BTDyA) featuring the extended donor-acceptor-donor structure through ethynyl group π-bridges connection (D--A--D). Compared to conventional D-A-D molecule (BTDA), BTDyA exhibits enhanced molar absorption coefficient and expanded powder absorption spectrum. Furthermore, transient absorption (TA) and photoinduced Raman spectroscopy revealed that upon photon absorption, the excited-state molecules of BTDyA undergo rapid excited-state decay accompanied by intense molecular vibrations, facilitating efficient conversion of photon energy to vibrational energy that ultimately manifests as the extremely high photothermal temperature. The BTDyA powder can reach 377 C under 1064 nm laser irradiation and 330 C under concentrated natural sunlight. Thanks to its exceptional solar-thermal conversion performance, BTDyA has been successfully applied in solar energy harvesting and thermal storage systems. This work provides fundamental insights into both synthetic strategies and photothermal conversion mechanisms for organic high-temperature photothermal materials, highlighting their potential for renewable energy applications.