Related Experiment Video
Updated: Jan 18, 2026

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Visible-Light-Controlled Thermal Energy Storage and Release: A Tetra-Ortho-Fluorinated Azobenzene-Doped Composite
Yating Zhang1,2, Jing Qi1,3, Jun Xia1
1Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou 310021, China.
None:
Organic phase change materials (OPCMs) offer high energy density for thermal storage but suffer from crystallization kinetics dependent on ambient temperature, leading to uncontrolled heat release and limited storage lifetime. Although doping OPCMs with azobenzene (Azo) derivatives enables optically controlled energy storage and release, existing systems require UV irradiation for E-to-Z isomerization. This UV dependency seriously hinders their development in practical solar applications. Herein, we develop a visible-light-responsive Azo@OPCM composite by doping tetra-ortho-fluorinated azobenzene into eicosane. Systematic characterization of composites with different dopant ratios via UV-visible spectroscopy and differential scanning calorimetry reveals that green-light irradiation drives E-to-Z isomerization, achieving 97-99% Z-isomer conversion. This photoisomerization could introduce supercooling through photo-responsive energy barriers generated by Z-isomer, allowing thermal energy storage at lower temperatures. Subsequent blue-light irradiation triggers Z-to-E reversion to eliminate supercooling and enable optically controlled heat release. Additionally, by regulating the molar ratios of dopant, the optimized composites achieved 280.76 J/g energy density at 20% molar doping ratio, which surpassed that of pure eicosane and the reported Azo-based photothermal energy storage system. This work establishes a complete visible-light-controlled energy harvesting-storage-release cycle with significant potential for near-room-temperature solar thermal storage applications.
Related Concept Videos
Phase Changes
A substance melts or freezes at a temperature called its melting point and boils or condenses at its boiling point. These temperatures depend on pressure. High pressure favors the denser form of the substance, so typically, high pressure...
Thermal Sigmatropic Reactions: Overview
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in 1,5-hexadiene, referred...
Phase Transitions: Vaporization and Condensation
Phase Transitions: Melting and Freezing
Phase Transitions
Thermal and Photochemical Electrocyclic Reactions: Overview

