Molecular Engineering of Vibronic Coupling Enables High‐Temperature Solar–Thermal Conversion in an Organic Material

ABSTRACT

Solar–thermal conversion offers a direct route for harvesting solar energy, yet most organic materials reported are limited to moderate temperatures and low‐temperature applications. Here, we report BTDyA, an organic material designed for high‐temperature solar–thermal conversion, achieved by bridging triphenylamine donors with [1,2,5]thiadiazolo[3,4‐f]benzotriazole acceptor via ethynyl linkages. BTDyA demonstrates a high molar absorption coefficient and broadband solid‐state absorption, enabled it to reach a temperature as high as 330 °C under concentrated outdoor sunlight, the highest reported value for organic solar–thermal materials. Moreover, under 1064 nm laser irradiation, the temperature could be further elevated to 377 °C. The transient absorption and photoinduced Raman spectroscopies reveal that BTDyA undergoes ultrafast nonradiative decay in the excited‐state, coupled with significant vibronic activation. These promote efficient conversion of photon energy into molecular vibronic energy and heat, while suppressing radiative losses and enhancing photothermal performance. The high‐temperature capability of BTDyA positions it as a promising candidate for solar energy harvesting and thermal storage. These findings offer critical insights into the design principles and photothermal mechanisms of organic materials for high‐temperature solar–thermal applications, paving the way for their future use in renewable energy technologies.