A highly efficient organic solar energy-absorbing material based on phthalocyanine derivative for integrated water evaporation and thermoelectric power generation application

Integrated water purification and electricity generation by photo-thermal effect has attracted great attention. However, the central issues are designs of the photothermal materials with efficient utilization of solar energy for water-electricity cogeneration. Herein, an organic-small-molecule phthalocyanine (Pc) derivative with polycyclic conjugated structure, 4OCSPC, has been synthesized. The alkoxy chains with high conformational flexibility were modified to alpha positions, and the thiophene groups were modified to beta positions, which afford this Pc derivative solution processing characteristic and enhance Pc conjugation. Therefore, 4OCSPC exhibits attractive photothermal properties and thermal/photo-stability. In solid state, 4OCSPC has a wide absorption range from 300 to 1000 nm, the molar extinction coefficient (epsilon) is 4.1 x 10(5) L mol(-1) cm(-1) in tetrahydrofuran (THF) at 800 nm, and the solar-thermal conversion efficiency is evaluated to be 17.3% under one sunlight irradiation. The solar-to-vapor efficiency was determined to be 86.6%, and the rate of water evaporation reached 1.262 kg m(-2) h(-1). Benefiting from the effective capillary action, a novel synergetically coupled solar-steam and solar-electricity device was designed and prepared, which can attain superior water purification and electricity generation performances. Our work demonstrates the application of photothermal organic-small-molecules with polycyclic conjugated structure in water evaporation and power generation, which provides potential opportunities for freshwater and electricity supply for remote areas.

Automated summary

By synthesizing the organic small molecule 4OCSPC, a material with efficient utilization of solar energy for water-electricity cogeneration has been successfully designed. This material exhibits excellent photothermal properties and thermal/photo-stability, achieving high efficiency water evaporation and power generation.