Highly Efficient NIR-II Photothermal Conversion Based on an Organic Conjugated Polymer

Development of special organic materials that are able to absorb light energy in the second near-infrared window (NIR-II) is significantly important for treating deep-tissue-buried diseases or supplying power to implantable electronic devices. Herein, a narrow bandgap donor–acceptor (D-A) conjugated polymer with thiophene-fused benzodifurandione-based oligo(p-phenylenevinylene) (TBDOPV) as acceptor part and 2,2′-bithiophene (DT) as donor part was developed and exploited as a photothermal conversion material with high extinction coefficient and robust photostability in the NIR-II window. According to transient absorption analysis results, the photothermal conversion ability of this polymer is attributed to the fast internal conversion (IC) process. The high photothermal conversion efficiency makes this polymer a promising NIR-II adsorbing antenna to remotely actuate thermo-dependent devices, e.g., high-performance photothermal–electrical and photothermal–mechanical converters.