Narrow-bandgap light-absorbing conjugated polybenzobisthiazole: Massive interfacial synthesis, robust solar-thermal evaporation and thermoelectric power generation

Exploiting advanced light-absorbing conjugated polymers is of great significance to achieve the blue dream of low-energy solar steam generation and clean water collection. Herein, an interfacial chemistry strategy is developed to massively synthetize conjugated polybenzobisthiazole (CP) microspheres with a narrow bandgap of 0.274 eV and high solar absorbance of 94.0%. The CP microspheres are combined with the polyvinyl alcohol (PVA) hydrogel to form a Janus evaporator. The evaporation rate and energy efficiency of the CP@PVA solar evaporator reach 2.96 kg m−2 h−1 and 98.8% with a low coating content of 5 mg cm−2. The evaporation performance of the Janus CP@PVA evaporator is applicable to seawater, sewage, and acid/alkali water. The efficient evaporator with portable collector can be simply assembled to produce drinking water from real seawater and sewage. Additionally, the Janus evaporator is also equipped with a thermoelectric module to generate the steam and electricity simultaneously. The power output achieves 1.04 W m−2 in real seawater while the evaporation rate remains 2.23 kg m−2 h−1 under 1 sun, demonstrating the remarkable capacity to utilize the solar energy.