Solar energy conversion and storage by photoswitchable organic materials in solution, liquid, solid, and changing phases

Qiu, Qianfeng; Shi, Yuran; Han, Grace G. D.

doi:10.1039/d1tc01472b

Cited by 62 publications

(61 citation statements)

References 116 publications

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“…Molecular solar thermal (MOST) systems have been recognized as a promising avenue to harvest and store thermal energy. [10][11][12][13][14][15] In the charging process, a stable isomer of a photochromic molecule absorbs photon energy and is converted into a high-energy metastable isomer, thereby storing solar energy in chemical bonds. The MOST system is discharged when the metastable isomer switches back to the stable isomer by external stimuli, with the release of stored energy in the form of heat.…”

Section: Introductionmentioning

confidence: 99%

A rechargeable molecular solar thermal system below 0 °C

et al. 2022

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Section: Introductionmentioning

confidence: 99%

A rechargeable molecular solar thermal system below 0 °C

et al. 2022

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“…However, the development of MOST systems is still in a nascent stage. [17] Many fundamental challenges and critical issues remain to be resolved such as the fact that the energy storage process of MOST systems is usually limited to UV light irradiation, which poses serious challenges for further practical applications. [13] Thus, more effort is needed to explore this huge research area.…”

Section: Phase Change Photoswitchesmentioning

confidence: 99%

Molecular Solar Thermal Systems towards Phase Change and Visible Light Photon Energy Storage

Wang

2022

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energy storage systems. [3] These photoswitches, which have the unique advantages of being environmentally friendly, easily transportable, rechargeable, and renewable, mainly include norbornadiene/quadricyclane (NBD/QC) couples, [4] dihydroazulene/vinylheptafulvene (DHA/ VHF) couples, [5] fulvalene dimetal complexes (FvRu2(CO)4), [6] and azobenzene compounds, [7] shown in Figure 1. Among them, the NBD/QC, DHA/VHF, and FvRu 2 (CO) 4 are usually studied in solution state or liquid-based flow systems, and they normally store the photon energy of UV light. [8] Azobenzene compounds, the most widely investigated molecular photoswitches, are considered to be the most promising candidates for the development of diversified MOST systems due to the easy functionalization, well-known trans/cis-configuration, altering physical properties. [9] The molecular photoswitches have been paid more and more attention for over 30 years. Yoshida in 1985, Brun et al. in 1991, and Dubonosov et al. in 2002 summarized the major findings and presented the basis for the development of early MOST systems. [10] It is noted that MOST systems should display high storage performances, high energy conversion efficiency, excellent cycling stability, and the ability to utilize light from a wide solar spectrum. [11] In recent years, many efforts have been made to overcome the abovementioned issues, and the applications of MOST systems have also been expanded significantly. [12] Feng and colleagues have comprehensively reviewed the progress of MOST systems from the perspective of design, properties, and applications. [13] Wu and coworkers have summarized the solar thermal energy conversion and storage of polymer-based MOST systems. [14] Moth-Poulsen and co-workers have systematically described the engineering of MOST systems for solar thermal energy storage applications, such as solution-state or liquid-based flow systems for solar water heating and thermal control of the built environment. [15] However, these reviews on MOST systems have focused on strategies to enhance the storage performances and develop applications, including molecular template assembly and molecular engineering. [16] The further development and application of MOST systems are still limited by storage energy density and UV light photon energy storage. [17] Fortunately, many pioneering works have been devoted recently to the development of MOST systems towards phase change (PC) characteristics and visible light photon energy storage. The PC characteristics

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“…Most recently, photoliquefiable azobenzene (Azo) molecules have shown significant potential for harvesting and storing thermal energy due to their reversible photoinduced crystal-to-liquid transitions (PCLTs), controllable heat storage and release, and zero gas/chemical emissions [15][16][17][18][19] . Han et al discovered three heat storage-release schemes for storing thermal energy in liquid-state cis-isomers [20] .…”

Section: Introductionmentioning

confidence: 99%

An azobenzene-based photothermal energy storage system for co-harvesting photon energy and low-grade ambient heat via a photoinduced crystal-to-liquid transition

Dong¹,

Zhai²,

Wang³

et al. 2022

Energy Mater

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Ambient heat, slightly above or at room temperature, is a ubiquitous and inexhaustible energy source that has typically been ignored due to difficulties in its utilization. Recent evidence suggests that a class of azobenzene (Azo) photoswitches featuring a reversible photoinduced crystal-to-liquid transition could co-harvest photon energy and ambient heat. Thus, a new horizon has been opened for recovering and regenerating low-grade ambient heat. Here, a series of unilateral para-functionalized photoinduced liquefiable Azo derivatives is presented that can co-harvest and convert photon energy and ambient heat into chemical bond energy and latent heat in molecules and eventually release them in the form of high-temperature utilizable heat. A straightforward crystalline-to-liquid phase transition achieved with ultraviolet light irradiation (365 nm) is enabled by appending a halogen/alkoxy group on the para-position of the Azo photoswitches, and the release of thermal energy is triggered by short-wavelength visible-light irradiation (420 nm). The phase transition properties of the trans- and cis-isomers and the energy density, storage lifetime and heat release performance of the cis-liquid are investigated with differential scanning calorimetry, ultraviolet-visible absorption spectroscopy, and an infrared (IR) thermal camera. The experimental results indicate a high energy density of 335 J/g, a long lifetime of 5 d and a heat release of up to 6.3 °C due to the coupled photochemical-thermophysical mechanism. This work presents a new model for utilizing renewable energy, i.e., the photoinduced conversion of ambient thermal energy.

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Solar energy conversion and storage by photoswitchable organic materials in solution, liquid, solid, and changing phases

Abstract: This review illustrates various structural design principles for molecular solar thermal (MOST) energy storage materials based on photoswitches that operate in different conditions, e.g. solution state, neat liquid, and solid,...

Cited by 62 publications

References 116 publications

A rechargeable molecular solar thermal system below 0 °C

A rechargeable molecular solar thermal system below 0 °C

Molecular Solar Thermal Systems towards Phase Change and Visible Light Photon Energy Storage

An azobenzene-based photothermal energy storage system for co-harvesting photon energy and low-grade ambient heat via a photoinduced crystal-to-liquid transition

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