Direct Sun-Driven Artificial Heliotropism for Solar Energy Harvesting Based on a Photo-Thermomechanical Liquid-Crystal Elastomer Nanocomposite

Inspired by heliotropism in nature, artificial heliotropic devices that can follow the sun for increased light interception are realized. The mechanism of the artificial heliotropism is realized via direct actuation by the sunlight, eliminating the need for additional mechatronic components and resultant energy consumption. For this purpose, a novel reversible photo-thermomechanical liquid crystalline elastomer (LCE) nanocomposite is developed that can be directly driven by natural sunlight and possesses strong actuation capability. Using the LCE nanocomposite actuators, the artificial heliotropic devices show full-range heliotropism in both laboratory and in-field tests. As a result, significant increase in the photocurrent output from the solar cells in the artificial heliotropic devices is observed.