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

Han, Grace G. D.; Li, Huashan; Grossman, Jeffrey C.

doi:10.1038/s41467-017-01608-y

Cited by 250 publications

(137 citation statements)

References 51 publications

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“…We based our hypothesis on prior works showing that small molecule azobenzenes (19,20) could undergo optically triggered crystal-to-crystal and crystal-to-liquid transitions, and azobenzene-containing polymers underwent optically triggered glass-to-liquid transitions (21). This phase-transition mechanism of azobenzene molecules has been studied to optically trigger the phase transition of organic phasechange materials in thermal energy storage systems (22,23).…”

Section: Resultsmentioning

confidence: 97%

Light-triggered thermal conductivity switching in azobenzene polymers

Shin

Sung

Kang

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

118

108

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Materials that can be switched between low and high thermal conductivity states would advance the control and conversion of thermal energy. Employing in situ time-domain thermoreflectance (TDTR) and in situ synchrotron X-ray scattering, we report a reversible, light-responsive azobenzene polymer that switches between high (0.35 W m−1K−1) and low thermal conductivity (0.10 W m−1K−1) states. This threefold change in the thermal conductivity is achieved by modulation of chain alignment resulted from the conformational transition between planar (trans) and nonplanar (cis) azobenzene groups under UV and green light illumination. This conformational transition leads to changes in the π-π stacking geometry and drives the crystal-to-liquid transition, which is fully reversible and occurs on a time scale of tens of seconds at room temperature. This result demonstrates an effective control of the thermophysical properties of polymers by modulating interchain π-π networks by light.

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Section: Resultsmentioning

confidence: 97%

Light-triggered thermal conductivity switching in azobenzene polymers

Shin

Sung

Kang

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

118

108

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“…During the holographic recording process, the azobenzene polymer is illuminated by two or more polarized interference beams, leading to the azobenzene groups reorienting perpendicularly to the polarization direction of light field and the formation of the photoinduced anisotropy, which is believed to result from the trans-cis-trans isomerization cycles of the azo-unit 22,23 . Particularly, azobenzene side-chain liquid-crystalline polymers have been found to be attractive owing to their large photoinduced birefringence and long-term optical storage 24,25 , so that more attention has been paid to the field of optical control with this kind of materials 26 .…”

Section: All-optically Phase-induced Polarization Modulation By Meansmentioning

confidence: 99%

All-optically phase-induced polarization modulation by means of holographic method

Lyu

Wang

2020

Sci Rep

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Methods Material preparation. The sample is a kind of supermolecular materials synthesized through the ionic self-assembly of poly ionic liquid and azobenzene dyes. The preparation process has been reported in ref. 47. For the preparation of ionic self-assembly complex, 2 mg/ml poly ionic liquid aqueous solution is added to methyl orange aqueous solution at the molar charge ratio of 1:1. The precipitated complex is filtrated and washed several times with doubly distilled water, then dried in vacuum at 60 °C for 12 h. The complex powder melts at 180 °C and the Schlieren textures appear during cooling.

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“…In the modern era, materials exhibiting different structures in different conditions have unique importance from an application point of view. Phase-change materials (PCMs), based on a structural transition [1][2][3][4][5][6], are potential candidates for thermal storage [7], drug delivery [8], data storage [1,9], image recording [10,11], near-infrared (NIR) transmission [12], etc.…”

Section: Introductionmentioning

confidence: 99%

Reduction of Rocksalt Phase in Ag -Doped Ge2Sb2Te5 : A Potential Material for Reversible Near-Infrared Window

Singh

Sharma

et al. 2018

Phys. Rev. Applied

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Phase-change materials are attracting much attention in the scientific and engineering communities owing to their applications and underlying basic phenomena. Ge 2 Sb 2 Te 5 is reversible-phase-change material (amorphous to crystalline and vice versa) that is used for optical data storage and phase-change random-access memory and has recently been explored for use as a reversible near-infrared (NIR) window [Singh et al., Appl. Phys. Lett. 111, 261102 (2017)]. For a reversible NIR window, large transmission contrast between two phases and low phase-transition temperature are required to reduce the power consumption. In the present work, phase transition in thermally deposited (Ge 2 Sb 2 Te 5) 100−x Ag x (x = 0, 1, 3, 5, and 10) thin films is achieved by vacuum thermal annealing. Transmission sharply decreases with phase transition in the NIR region. Ge 2 Sb 2 Te 5 shows large transmission contrast (more than 50%) in the wavelength range from 1600 to 3200 nm with phase transition from an amorphous to a hexagonal-closepacked structure at 260 • C. In (Ge 2 Sb 2 Te 5) 90 Ag 10 thin films, a similar transmission contrast is achieved at a comparatively lower temperature (160 • C) due to reduction of the rocksalt phase. Distortion of the host lattice with addition of 10% Ag is confirmed from the drastic change in the density of states in the valence band and the shift in core-level (3d) spectra of Ag, Sb, and Te. This distortion enables a hexagonal-closepacked phase in (Ge 2 Sb 2 Te 5) 90 Ag 10 thin films to be obtained at 160 • C. (Ge 2 Sb 2 Te 5) 90 Ag 10 could be a potential candidate for a reversible NIR window as it requires less power to achieve phase transition and high transmission contrast.

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

Cited by 250 publications

References 51 publications

Light-triggered thermal conductivity switching in azobenzene polymers

Light-triggered thermal conductivity switching in azobenzene polymers

All-optically phase-induced polarization modulation by means of holographic method

Reduction of Rocksalt Phase in Ag -Doped Ge2Sb2Te5 : A Potential Material for Reversible Near-Infrared Window

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