Sunlight-activated phase change materials for controlled heat storage and triggered release

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 9; no. 15; pp. 9798 - 988
• Main Authors: Shi, Yuran, Gerkman, Mihael A, Qiu, Qianfeng, Zhang, Shuren, Han, Grace G. D
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2021
• Subjects: Azo compounds; Crystallization; Energy; Energy harvesting; Heat; Heat storage; Irradiance; Irradiation; Isomerization; Latent heat; Light sources; Liquid phases; Luminous intensity; Organic materials; Phase change materials; Phase transitions; Photovoltaics; Solar energy; Solar radiation; Sunlight; Switches; Wavelengths
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d1ta01007g

We report the design of photo-responsive organic phase change materials that can absorb filtered solar radiation to store both latent heat and photon energy via simultaneous phase transition and photo-isomerization. The activation of photo-switches by long wavelengths ≥530 nm in the visible light range at a low irradiance is achieved, in the absence of high-intensity light sources, by the ortho -substitution of azobenzene units. The facile transition from crystalline to liquid phase is enabled by appending an aliphatic group on the photochromic moiety. The sunlight-activated liquid phase exhibits an exceptionally long heat storage without crystallization for nearly two months, and the release of energy is triggered by a short irradiation at 430 nm. The successful demonstration of photo-controlled latent heat storage accomplished by solar irradiation opens a new horizon on solar energy harvesting by functional organic materials, as a complementary system to photocatalysts and photovoltaic materials. Photo-responsive organic phase change materials that can absorb filtered solar radiation in the visible range to store both latent heat and photon energy are demonstrated.