Photo-thermoelectric conversion and photo-induced thermal imaging using 2D/3D ReS2@carbon framework with enhanced photon harvesting

Solar energy is a promising renewable energy with the potential for the sustainable development of the world. Efficient photo-thermal conversion is essential for harvesting and conversion of solar energy, therefore, the main challenge is the development of efficient and low-cost photothermal conversion materials. Carbon framework can be considered as a candidate but somehow its application potential can be still constrained due to the limited absorption of near-infrared (NIR) light. Herein, we propose a general strategy for preparing two-dimensional (2D) transition metal dichalcogenides nanosheets and three-dimensional (3D) carbon framework composites (2D/3D ReS2@C) as a photothermal material, which has an excellent broadband light absorption performance (in the wavelength range from 200 to 2500 nm). A small thermoelectric (TE) module with an area of 4 x 4 cm2 is integrated with annealed ReS2@C as a light absorber for the investigation of photo-thermoelectric conversion. The open-circuit voltage of the assembled device increases clearly under solar illumination and reaches the maximum value of 136.3 mV, which is - five times larger than that without the absorber. In addition, 20 TE modules coated with ReS2@C absorber layers are connected in series, which can produce a maximum opencircuit voltage of 2.12 V (-66.25 V/m2) to light up a red light-emitting diode (LED) under natural sunlight. Moreover, the annealed ReS2@C powder demonstrates a rapid and strong photothermal response under NIR light (wavelength >800 nm), which indicates a great application potential in photothermal imaging and photothermal cancer therapy.