Photochemical crystal-to-liquid transition generally needs UV light as a stimulus and it is even more challenging to carry out below 0 oC. Here, we design a series of 4-alkylthioarylazopyrazoles as molecular solar thermal batteries, which show bidirectional visible-light-triggered photochemical trans-crystal ↔ cis-liquid transitions below ice point (-1 oC). Through co-harvesting visible-light energy and low-temperature ambient heat, high energy density (0.25 MJ kg-1) is achieved. Further, the rechargeable solar thermal batteries devices are fabricated, which can be charged by blue light (400 nm) at -1 oC. Then, the charged devices can release energy on demand in the form of high-temperature heat. Under green light (532 nm) irradiation, the temperature difference between the charged devices and the ice-cold surrounding is up to 13.5 oC. This study paves the way for the design of advanced molecular solar thermal batteries that store both natural sunlight and ambient heat over a wide temperature range.

中文翻译：

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通过偶氮吡唑的可见光控制光化学相变，在 0 oC 以下共同收集太阳能与环境热和按需释放热能

光化学晶体到液体的转变通常需要紫外光作为刺激，而在 0 oC 以下进行则更具挑战性。在这里，我们设计了一系列 4-烷基硫代芳基并吡唑作为分子太阳能热电池，在冰点 (-1 oC) 以下显示双向可见光触发的光化学跨晶↔ 顺式液体转变。通过共同收集可见光能量和低温环境热量，实现了高能量密度（0.25 MJ kg-1）。此外，还制作了可充电太阳能热电池装置，可在-1 oC 下通过蓝光（400 nm）充电。然后，带电设备可以根据需要以高温热量的形式释放能量。在绿光 (532 nm) 照射下，带电设备与冰冷环境之间的温差高达 13.5 oC。