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

Abstract

Recently, organic photothermal materials have shown great application potential for solar-driven water−electricity co-generation. However, their extended application is limited by low solar-heat conversion efficiency. This study designed a planarized donor−acceptor (D−A)-type organic photothermal material 5,18-dibutyl-5,18-dihydrodiquinoxaline[2,3-a:2′,3′-c]phenazine (DDHT) by fusing a strongly electron-donating arylamine unit and strongly electron-withdrawing quinoxalino[2,3-a]phenazine unit. The fused-ring D−A structure not only endowed the material with broad absorption spectra through low-energy intramolecular charge−transfer transition, but also allowed for intense intermolecular π−π interactions, which improve nonradiative transition probability and, correspondingly, the photothermal conversion efficiency (58.58% under laser irradiation at 655 nm). Under a solar intensity of 1 kW m −2 , the water evaporation rate was 1.13 kg m −2 h −1 with a solar-to-vapor efficiency of 78.40% for the DDHT-based interfacial evaporation devices. Finally, a solar-driven steam and electricity co-generation device was prepared with the DDHT/wood composite as the solar-evaporator material, demonstrating electricity generation performances and excellent water purification capabilities. Our research found that fused-ring D−A structures are promising organic photothermal systems for efficient solar-heat conversion.

A narrow-bandgap photothermal material based on a donor–acceptor structure for the solar–thermal conversion application

“…S9, ESI †). Compared with other organic photothermal materials, 14,[34][35][36]62 the photothermal conversion efficiency of the 2TP-BBT material is good (Table S2, ESI †).…”

“…The evaporation rate of the water–electric cogeneration device is 1.22 kg m −2 h −1 , and the output voltage is 57.1 mV. Comparing the thermoelectric properties of reported organic photothermal materials, 34–37 it is found that the thermoelectric power generation properties of the 2TP-BBT material are excellent (Table S1, ESI†). The thermoelectric power generation and water–electricity cogeneration under solar illumination offer a valuable prospect of utilization in efficient solar thermal energy conversion to solar water evaporation and power generation applications.…”

PDI‐Based Organic Small Molecule Regulated by Inter/Intramolecular Interactions for Efficient Solar Vapor Generation

“…The PDI core with planar and rigid multi-ring 𝜋electron conjugation system causes PDI-DTMA molecule to aggregate through intermolecular 𝜋-𝜋 interaction, favorable for broadening the absorption spectrum and strengthening the photothermal conversion. [9,12,15,16,18] Additionally, the electrondonating 3,4,5-trimethoxyphenyl moieties are strategically attached to the imide positions of the electron-accepting PDI core, resulting in the D-A-D configuration of PDI-DTMA. [27,28] The modification of the electron donor to the acceptor can reduce the band gap, so as to achieve the optimization of light absorption and photothermal conversion.…”

“…Strategies, such as regulation of molecular stacking, enhancement of intramolecular charge transfer, introducing intramolecular motion and free radicals, have been employed to narrow the band gap, thereby maximizing photothermal conversion efficiency. [10][11][12][13][14][15][16][17][18][19] Despite these efforts, the number of available organic small molecules for solar water evaporation remains limited. Additionally, most of these evaporators lack subtle design, resulting in unsatisfactory water evaporation rates (<1.55 kg m −2 h −1 under 1 kW m −2 ), which are lower than recently reported evaporation rates.…”

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

“…Nowadays, the common organic photothermal materials are organic small molecular dyes of porphyrin, 11 indocyanine green, 12 and phthalocyanine 13 and polymers of polyaniline (PAN), 14 polydopamine 10,15 and polypyrrole (PPY), 16 diketone pyrrole, 17 and other donor-acceptor conjugate compounds. 18,19 However, the electron localization characteristic of organic materials makes fine-scale tunability in band structure difficult, which brings challenges to molecular design and organic synthesis process.…”