Fully Conjugated Covalent Porous Polymers for Highly Efficient Solar-Thermal Conversion

Solar-thermal water evaporation is a promising strategy for the clean water production. Developing photothermal conversion materials with high efficiency and stability is both urgent and challenging. Herein, we report two fully conjugated bipyranylidene-based microporous polymers (DP-CMP1 and DP-CMP2) for the first time, that feature broad light absorption, superior photothermal efficiency, and outstanding durability. Under the illumination of 660 nm laser with 100 mW cm –2, the temperature of DP-CMP1 drastically increased from 29.1 to 174.7 °C within 4 s. Furthermore, an interfacial heating evaporation system based on DP-CMP1 achieved high solar thermal water evaporation rates of 3.83 and 3.77 kg m –2 h –1 under 1 sun illumination for pure water and seawater, with excellent energy conversion efficiency of 97.5 and 96.6%, respectively. Multiple spectroscopic and theoretical investigations reveal DP-CMP1 is intrinsically an outstanding photothermal material owing to its small band gap, fast nonradiative combination rate, large nonadiabatic coupling value, and stronger electron–phonon coupling.