Photon energy storage materials with high energy densities based on diacetylene–azobenzene derivatives

Abstract

Photocontrolled self-assembly of molecules has been utilized to change the physical properties of organic materials for various applications, while photon energy storage materials that incorporate photochromic molecules such as azobenzenes have been recognized as another highly attractive class of materials that convert and store photon energy in the strained chemical bonds. Herein, we demonstrate the photocontrolled self-assembly and disassembly of photon energy storage materials based on new diacetylene derivatives with azobenzene moieties and with varied alkyl spacers and linkers. We

Optically-controlled long-term storage and release of thermal energy in phase-change materials

“…If it is 100% doped, the pristine azobenzene dopant has a potential to release 234 J g −1 of heat, but the requirement of heating it above its high T m (73 °C) for the solid-state charging induces the thermal reverse isomerization of the cis isomer, preventing the control over thermal storage. Also, UV illumination of azobenzene in the solid state without heating is ineffective as a result of steric confinement of aromatic groups in the crystalline lattice 32 . Thus, the design of PCM and the azobenzene composite has a unique advantage to realize thermal storage at temperatures above the relatively low T m of the PCM.…”

“…The energy-storage capacity of pristine azobenzene as an STF is 0.23 kJ g −1 31 , while the input UV (365 nm) photon energy density is 18.0 kJ g −1 (1.3% efficiency). Other azobenzene derivatives that exhibit higher energy storage as a result of structural designs provide slightly improved efficiencies such as 2.7% 32 and 3.0% 43 , assuming approximately 10% quantum yield. Utilizing azobenzene photoswitches as a minor component in the PCM composite gives rise to the relatively low demand for photon energy input, compared to that for STFs that consist of 100% photoswitches.…”

Intermolecular London Dispersion Interactions of Azobenzene Switches for Tuning Molecular Solar Thermal Energy Storage Systems

“…For example the introduction of fluorine atoms as well as methoxy groups shift the absorption to longer wavelength. There have been different strategies to increase the storage energy . Stabilizing groups can influence the ( E )‐( Z )‐energy difference even by subtle interactions such as London dispersion .…”

Demonstration of an azobenzene derivative based solar thermal energy storage system

“…The MOST concept has been represented by many potential candidates, including norbornadiene/quadricyclane derivatives, 7,9-14 dihydroazulene/vinylheptafulvene couples, [15][16][17][18][19][20][21] difulvalenediruthenium complexes, 6 anthracene dimers, 22 Dewar isomers 23 and azobenzene derivatives. 8,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] The last systems have been in the spotlight recently due to the broad absorption spectrum, high robustness, daily storage half-life, tunable energy density (J mol À1 ) of photoswitches, and the low synthetic cost. [40][41][42] AZO1 (see Fig.…”

“…8,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] The last systems have been in the spotlight recently due to the broad absorption spectrum, high robustness, daily storage half-life, tunable energy density (J mol À1 ) of photoswitches, and the low synthetic cost. [40][41][42] AZO1 (see Fig. 1a) possesses many of the needed features described above; however it has not been tested in a full MOST operating cycle including energy capture, storage and release.…”