Temperature‐Responsive Thermochromic Phase Change Materials with Tunable Photothermal Conversion Efficiency Toward Solar Energy Storage

Abstract There are many reports in the literatures on the use of phase change materials (PCMs) with photothermal conversion to store and harness solar energy. However, few works have reported intelligent PCMs with thermochromic capabilities that can controllably adjust their photothermal conversion efficiency to change the heating rate through temperature response. In this work, thermochromic phase change materials (TC‐PCMs) are successfully prepared by integrating the reversible thermochromic microcapsules into dynamically cross‐linked PCMs. The designed TC‐PCMs have a high photothermal conversion efficiency by using different styles of reversible thermochromic microcapsules, which can intelligently adjust the surface color of TC‐PCMs according to the substrate temperature under illumination conditions. Based on the fast temperature‐responsive thermochromic function of TC‐PCMs, the intriguing function of the reversible information storage and encryption can be realized by designing the shape and space of TC‐PCMs under the only thermal‐triggered condition. Importantly, the process of information storage and encryption can be controllable and reversible when repeatedly increasing and decreasing the external temperature. Additionally, TC‐PCMs capable of reprocessing ability based on dynamic oxime bond, are beneficial to the preparation of complex shape devices and recycling, expanding the application field of TC‐PCMs.