Conventional thermophysical latent heat storage based on solid-liquid phase change materials (PCMs) has been suffering three long-standing bottlenecks—i.e., relatively low storage density, short storage duration, and heat degradation during one charging/discharging cycle. In this perspective, we introduce a class of recently developed photoswitchable PCMs that have the potential to address these issues. Such PCMs present simultaneously the photon-induced molecule isomerization and thermally induced solid-liquid phase change, which endows them with dual and switchable phase change behaviors. This unique characteristic opens up new paths for exploring the unconventional thermal energy storage and upgrade technologies and even developing novel solar thermal fuels. However, there is still a long way to go for the practical applications of these materials and the derived technologies. Tuning the thermodynamic parameters, enhancing kinetics of isomerization and phase change, improving energy conversion efficiency, and modulating the absorption spectrum are four key issues that need further consideration. This article systematically summarizes the progress in photoswitchable PCMs, provides a deep insight into their potential applications, analyzes the challenges ahead, and proposes future research directions and solutions to continue the path.

基于固液相变材料 (PCM) 的传统热物理潜热存储一直面临三个长期存在的瓶颈——即存储密度相对较低、存储持续时间短以及在一个充电/放电循环中的热降解。从这个角度来看，我们介绍了一类最近开发的光开关 PCM，它们有可能解决这些问题。这种 PCM 同时存在光子诱导的分子异构化和热诱导的固液相变，这赋予它们双重和可切换的相变行为。这一独特的特性为探索非常规热能储存和升级技术，甚至开发新型太阳能热燃料开辟了新途径。然而，这些材料及其衍生技术的实际应用还有很长的路要走。调整热力学参数、增强异构化和相变动力学、提高能量转换效率和调节吸收光谱是需要进一步考虑的四个关键问题。本文系统地总结了光开关 PCM 的进展，深入了解其潜在应用，分析了未来面临的挑战，并提出了未来的研究方向和解决方案，以继续这条道路。