Organic Charge-Transfer Cocrystals toward Large-Area Nanofiber Membrane for Photothermal Conversion and Imaging

Abstract

Organic photothermal materials integrating a high-efficiency light–heat conversion effect and high flexibility have generated immense interest in fundamental research and practical applications. Nevertheless, their practical applications still remain a challenge, owing to the complicated design, tedious synthesis, and limited programmable substrates. Herein, an organic charge-transfer cocrystal with a narrow energy gap of 0.33 eV and a high photothermal conversion efficiency (PCE) of 69.3% was rationally designed and synthesized via a facile self-assembly process, which was introduced into polyurethane for forming a large-area photothermal nanofiber membrane via electrospinning technology. Femtosecond transient absorption spectroscopy elucidates that the excellent PCE is attributed to the nonradiation transition process, including internal conversion and charge dissociation processes. Furthermore, the temperature of the as-prepared photothermal nanofiber membrane could quickly rise to 52 °C under laser irradiation with a power density of 0.183 W/cm2, suggesting a high PCE of 53.7%. This work successfully achieves the fabrication of a large-area photothermal membrane and the development of photothermal imaging.

Organic photothermal cocrystal with high stability for efficient solar-driven water evaporation

“…27 In this condition, several charge-transfer cocrystals with wide absorption and high photothermal conversion efficiency have been developed recently. 28–30 Li et al 31 loaded the classical TTF-based cocrystals into polydimethylsiloxane (PDMS) and constructed CCTC-S scaffolds, which proved the possibility of photothermal cocrystals in the field of water evaporation for the first time. Then benzophenones were used to prepare photothermal AFQ cocrystals and displayed a water evaporation efficiency of 60.53%.…”

Boosting Water Evaporation by Construction of Photothermal Materials with a Biomimetic Black Soil Aggregate Structure

“…It is worth noting that in addition to the ideal design of salt management, the photothermal evaporation layer materials are also put forward higher requirements. At present, metal-based inorganic materials, 35 carbon-based inorganic materials, 36 organic−inorganic hybrid materials, 37 polymer materials, 38 organic eutectic materials, 39 pure organic small molecule materials, 40 and biomass-based materials 41 have been developed for solar-powered evaporation devices. However, in the process of constructing the evaporation layer with various photothermal materials, few people pay attention to the effect of the aggregation effect of the material itself on the transport of water and light utilization.…”

Dual Charge Transfer Generated from Stable Mixed‐Valence Radical Crystals for Boosting Solar‐to‐Thermal Conversion

“…[21] Benefitting from the effective CT and the diversity of components, organic cocrystals can be designed with flexible light absorption to meet different application requirements, which is difficult to achieve with traditional photothermal materials. [22] Moreover, precise cocrystal architectures offer the opportunity to unveil the structure-property and charge transferproperty relationships. [23] In this work, we design a stable mixed-valence radical crystal, 2TTF-2TTF +• -2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)-2H 2 O, namely TTF-(TTF +• ) 2 -RC, containing both IVCT and IRCT by using surfactant-mediated cocrystallization method.…”