Janus Helical Ribbon Structure of Ordered Nanowire Films for Flexible Solar Thermoelectric Devices

Abstract Solar thermoelectric devices play a significant role in addressing the problem of global warming, owing to their unique features of converting both waste heat and solar energy directly into electricity. Herein, a flexible 3D Janus helical ribbon architecture is designed, starting from well‐aligned tellurium (Te) nanowire film, using an in situ redox process reacting with Ag + and Cu 2+ resulting in n‐type, p‐type, and photothermal sides in one film. Remarkably, the device shows all‐day electricity generation and large temperature gradient by coupling the cold side with a passive radiative cooling technique and the hot side with a selective solar absorption technique, showing a temperature gradient of 29.5 K, which is much higher than previously reported devices under a low solar radiation of only 614 W m −2 . Especially, the device can still generate electricity even at night. The present strategy offers a new way for heat management by efficiently utilizing solar energy and the cold of the universe.