Precise Tuning Near-Infrared Photothermal Conversion of Ternary Cocrystals via Supramolecular Interactions

Abstract

Effective utilization of solar energy through cocrystal strategy is still a considerable challenge. Herein, the ternary cocrystal strategy is subtly applied to broaden the absorption of cocrystals, resulting in an efficient solar photothermal conversion (PTC). Specifically, the donors of triphenylene (T) and perylene (P) and guest molecules anthracene (AT), pyrene (PY), and perylene (P) are self-assembled with 7,7,8,8-tetracyanoquinodimethane (TCNQ) to obtain five ternary cocrystals (AT-T-TCNQ, PY-T-T-TCNQ, AT-P-TCNQ, PY-P-TCNQ, and P-P-TCNQ). The PTC of ternary cocrystals can be regulated by changing the number of benzene rings of donor and guest molecules, which may be attributed to the pi-pi and C-H center dot center dot center dot pi intermolecular interactions. Femtosecond transient absorption and excited-state theoretical calculations confirm that the intense pi-pi stacking interactions facilitate the light-harvesting capability, while the weak C-H center dot center dot center dot pi interactions are conducive to molecular stacking loosening and thus facilitate the rotation of C(C equivalent to N)(2), which promotes nonradiative transition to achieve the efficient PTC. As expected, the PTC efficiencies of AT-T-TCNQ, PY-T-TCNQ, AT-P-TCNQ, PY-P-TCNQ, and P-P-TCNQ are 59.62%, 63.07%, 81.72%, 79.06%, and 87.72%, respectively, under 808 nm irradiation. Due to the P-P-TCNQ having excellent near-infrared PTC efficiency, it is applied in a solar-driven interfacial heating evaporation system, gaining a decent evaporation efficiency (83.1%).