Azobenzene-Based Solar Thermal Fuels: A Review

Abstract

The energy storage mechanism of azobenzene is based on the transformation of molecular cis and trans isomerization, while NBD/QC, DHA/VHF, and fulvalene dimetal complexes realize the energy storage function by changing the molecular structure. Acting as “molecular batteries,” they can exhibit excellent charging and discharging behavior by converting between trans and cis isomers or changing molecular structure upon absorption of ultraviolet light. Key properties determining the performance of STFs are stored energy, energy density, half-life, and solar energy conversion efficiency. This review is aiming to provide a comprehensive and authoritative overview on the recent advancements of azobenzene molecular photoswitch system in STFs fields, including derivatives and carbon nano-templates, which is emphasized for its attractive performance. Although the energy storage performance of Azo-STFs has already reached the level of commercial lithium batteries, the cycling capability and controllable release of energy still need to be further explored. For this, some potential solutions to the cycle performance are proposed, and the methods of azobenzene controllable energy release are summarized. Moreover, energy stored by STFs can be released in the form of mechanical energy, which in turn can also promote the release of thermal energy from STFs, implying that there could be a relationship between mechanical and thermal energy in Azo-STFs, providing a potential direction for further research on Azo-STFs.

Light-responsive bent-core liquid crystals as candidates for energy conversion and storage

“…Even though azobenzenes have been studied for several decades [5][6][7], they continue to attract interest due to their potential to promote long-range macroscopic changes induced by short-range molecular modifications. [8][9][10][11][12] Bent-core liquid crystals, BCLCs, exhibit anti-ferroelectric and ferroelectric behaviour with high figures of merit, which can be useful for energy storage applications. BCLCs can form columnar (Col, former B 1 ), polar smectic C (SmCP, former B 2 ), twist grain boundary dark conglomerate (DC) or helical nanofilament (HNF, former B 4 ) phases among others [13][14][15][16][17][18][19][20].…”

“…Even though azobenzenes have been studied for several decades, 5–7 they continue to attract interest due to their potential to promote long-range macroscopic changes induced by short-range molecular modifications. 8–12…”

Solar–Thermal Fuels and the Role of Carbon Nanomaterials: A Perspective with Emphasis on the Azobenzene System

“…Therefore, it is important to understand the nature of the interactions between AB-derivatives and carbon nanomaterials as well as to discuss the different experimental techniques allowing the characterization of the AB-CNM composites. These topics were recently reviewed. ,, …”

Azobenzene-decorated cellulose nanocrystals as photo-switchable chiral solutes in nematic liquid crystals

“…The reversible photoisomerization of azobenzenes has been and still is used in an extensive array of materials systems and for applications ranging from catalysis [44][45][46] over energy harvesting 47 and actuators 48 to countless optical applications. 49,50 The latter presumably receiving the bulk of attention because of the robust and well-understood trans-cis photoisomerization of azobenzene derivatives that can be switched by a combination of light at various wavelengths and temperatures.…”