Diradical‐Featured Organic Small‐Molecule Photothermal Material with High‐Spin State in Dimers for Ultra‐Broadband Solar Energy Harvesting

Abstract

Organic materials with radical characteristics are gaining increasing attention, due to their potential implications in highly efficient utilization of solar energy. Manipulating intermolecular interactions is crucial for tuning radical properties, as well as regulating their absorption bands, and thus improving the photothermal conversion efficiency. Herein, a diradical‐featured organic small‐molecule croconium derivative, CR‐DPA‐T, is reported for highly efficient utilization of solar energy. Upon aggregation, CR‐DPA‐T exists in dimer form, stabilized by the strong intermolecular π–π interactions, and exhibits a rarely reported high‐spin state. Benefiting from the synergic effects of radical characteristics and strong intermolecular π–π interactions, CR‐DPA‐T powder absorbs broadly from 300 to 2000 nm. In‐depth investigations with transient absorption analysis reveal that the strong intermolecular π–π interactions can promote nonradiative relaxation by accelerating internal conversion and facilitating intermolecular charge transfer (ICT) between dimeric molecules to open up faster internal conversion pathways. Remarkably, CR‐DPA‐T powder demonstrates a high photothermal efficiency of 79.5% under 808 nm laser irradiation. By employing CR‐DPA‐T as a solar harvester, a CR‐DPA‐T‐loaded flexible self‐healing poly(dimethylsiloxane) (H‐PDMS) film, named as H‐PDMS/CR‐DPA‐T self‐healing film, is fabricated and employed for solar–thermal applications. These findings provide a feasible guideline for developing highly efficient diradical‐featured organic photothermal materials.

High-Performance Organic Photothermal Material Based on Fusion of the Donor–Acceptor Structure for Water Evaporation and Thermoelectric Power Generation

“…The shortage of freshwater resources has become one of the most serious challenges limiting the future growth of human civilization. − Compared with the scarcity of freshwater resources, the earth’s oceans are extremely rich in seawater resources. Therefore, developing an efficient desalination method can effectively resolve the freshwater shortage. − Currently, the most widely used seawater desalination technologies are reverse osmosis membranes, , multistage flash desalination, and multi-effect distillation . However, these technologies generally consume a large amount of energy and even cause environmental pollution during their utilization. − Solar energy is the cleanest type of energy, and in order to make more efficient use of solar energy, the evaporator structure and performance should be fully understood. − So far, interfacial solar evaporation technology has become the best solution to solve the freshwater crisis. − The design of photothermal materials with extensive solar energy absorption and high photothermal conversion efficiency has become the focus of related research. − Currently, photothermal materials are mainly divided into metal-based inorganic materials, , carbon-based inorganic materials, , polymeric materials, and organic small-molecule materials. − Among these, organic small-molecule photothermal materials have the advantages of a high degree of structural tunability, processing feasibility, and good flexibility. − The development of organic small-molecule photothermal materials with extensive light absorption and excellent photothermal conversion efficiency presents a possibility for solar-driven water evaporation.…”

Vertically π-extended strong acceptor unit boosting near-infrared photothermal conversion of conjugated polymers toward highly efficient solar-driven water evaporation

“…Agents with desirable photothermal conversion efficiency are in urgent pursuit as they not only signicantly promote biological applications, 1,2 including photoacoustic imaging (PAI) and photothermal therapy (PTT), but also help advance their appealing applications in solar energy utilization, 3 such as solar-driven seawater desalination 4,5 and solar thermoelectric generation. [6][7][8] With the development of industry and increased population, the shortage of clean water will be one of the biggest threats to mankind. [9][10][11][12] Solar-driven seawater desalination is an effective means to address this problem through utilizing the ubiquitous and green solar energy.…”

“…[43][44][45] Additionally, recent studies conrmed that strong p-p stacking interactions in the solid state could help to convert the excited energy dissipation process from radiative decay to a thermal deactivation process for heat generation. 7,46,47 With this mind, herein, we installed a strong acceptor unit, benzothiadiazole-fused acenaphthenequinone imide (BOBT), into D-A copolymers, expecting to push the absorption into the NIR region and thus boost solar-thermal conversion. BOBT was chosen among the known strong acceptor units based on the following considerations (Fig.…”

High‐Entropy‐Alloy‐Nanoparticles Enabled Wood Evaporator for Efficient Photothermal Conversion and Sustainable Solar Desalination

“…Photothermal conversion materials have attracted considerable interest in solar steam generation because of the requirements of seawater desalination and wastewater purification. [1][2][3][4][5][6][7] Their conversion efficiencies are related to the optical absorption performances over the entire solar spectrum (250-2500 nm), [8][9][10] in which various innovative mechanisms have been reported. For example, plasmonic heating behaviors of metallic HEA-NPs and the hydrophilic balsawood matrixes to achieve high photothermal conversion performance and solve the salt accumulation problem, denoted as x-HEA-BW (x stands for the composed elements number of HEA-NPs).…”