Open‐shell Poly(3,4‐dioxythiophene) Radical for Highly Efficient Photothermal Conversion

Abstract

AbstractOpen‐shell organic radical semiconductor materials have received increasing attention in recent years due to their distinctive properties compared to the traditional materials with closed‐shell singlet ground state. However, their poor chemical and photothermal stability in ambient conditions remains a significant challenge, primarily owing to their high reactivity with oxygen. Herein, a novel open‐shell poly(3,4‐dioxythiophene) radical PTTO2 is designed and readily synthesized for the first time using low‐cost raw material via a straightforward BBr3‐demethylation of the copolymer PTTOMe2 precursor. The open‐shell character of PTTO2 is carefully studied and confirmed via the signal‐silent 1H nuclear magnetic resonance spectrum, highly enhanced electron spin resonance signal compared with PTTOMe2, as well as the ultra‐wide ultraviolet‐visible‐near nfraredUV–vis–NIR absorption and other technologies. Interestingly, the powder of PTTO2 exhibits an extraordinary absorption range spanning from 300 to 2500 nm and can reach 274 °C under the irradiation of 1.2 W cm−2, substantially higher than the 108 °C achieved by PTTOMe2. The low‐cost PTTO2 stands as one of the best photothermal conversion materials among the pure organic photothermal materials and provides a new scaffold for the design of stable non‐doped open‐shell polymers.