Molecular solar thermal (MOST) materials, which can efficiently capture solar energy and release it as heat on demand, are promising candidates for future personal thermal management (PTM) applications, preferably in the form of fabrics. However, developing MOST fabrics with high energy‐storage capacity and stable working performance remains a significant challenge because of the low energy density of the molecular materials and their leakage from the fabric. Here, an efficient and robust MOST fabric for PTM using azopyrazole‐containing microcapsules with a deep‐UV‐filter shell is reported. The MOST fabric, which can co‐harvest solar and thermal energy, achieves efficient photocharging and photo‐discharging (>90% photoconversion), a high energy density of 2.5 kJ m−2, and long‐term storage sustainability at month scale. Moreover, it can undergo multiple cycles of washing, rubbing, and recharging without significant loss of energy‐storage capacity. This MOST microcapsule strategy is easily used for the scalable production of a MOST fabric for solar thermal moxibustion. This achievement offers a promising route for the application of wearable MOST materials with high energy‐storage performance and robustness in PTM.

Following the progress on mono‐heteroaryl azo switches (Het‐N=N‐Ph), a few bis‐heteroaryl azo switches (Het‐N=N‐Het) have been studied recently, whereas the nonsymmetric bis‐heteroaryl ones (Het1‐N=N‐Het2) that can combine the respective merits of each heterocycle, have received little attention. Here we report thiazolylazopyrazoles as nonsymmetric bis‐heteroaryl azo switches that combine the visible‐light switching character of the thiazole ring and the ease of o‐substitution of the pyrazole ring. Thiazolylazopyrazoles can achieve (near‐)quantitative visible‐light isomerization in both directions and long Z‐isomer thermal half‐lives of several days. In contrast to the drastically destabilizing effect of o‐methylation, o‐carbonylation of the pyrazole ring can remarkably stabilize Z isomers by inducing attractive intramolecular interactions (dispersion, C−H⋅⋅⋅N bond, and lone‐pair⋅⋅⋅π interaction). Our work highlights the importance of the rational combination of two heterocycles and suitable structural substitution in developing bis‐heteroaryl azo switches.

By absorbing light energy, molecular photoswitches can undergo structural changes, store chemical energy, and perform dynamic work, which has profound impacts on the development of stimuli-responsive systems, energy storage/conversion materials, artificial molecular machines, etc. Developing photoswitches that can be fueled by natural sunlight will bring great benefits to their applications in the context of carbon neutrality. Here, we show that solar photoswitching can be realized by reshaping the absorption spectral profile, i.e., rendering the absorption of parent isomer overwhelmingly stronger than that of metastable isomer across the UV–Vis spectra. Solar E→Z photoisomerization of azo molecules—the most widely used class of photoswitches—are achieved by implementing this spectral tuning principle. A simple yet tunable molecular design strategy to meet this spectral requirement is established and a variety of solar photoisomerizable heteroaryl-based azo-switches are developed. Photoswitching under natural sunlight in place of the traditional artificial lights represents a crucial step towards sustainable light-driven processes.