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

Abstract

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.

Reversible Photo Actuated Bulk Nanocomposite with Nematic Liquid Crystalline Elastomer Matrix

“…The LCE matrix was held in the inter pores of the 3D polyurethane skeleton network, which not only serves as a mechanical reinforcement matrix, but also would effectively exert its elasticity to assist in the reversible actuation process. From the material synthesis perspective, the utilization of polyurethane skeleton network as a full 3D elastic scaffold here is a key advance compared with the polyurethane fiber-network/SWCNT/LCE composite films reported in our previous work [22]. After this first stage of crosslinking, the pores of the polyurethane porous foam were fully filled by the partially crosslinked swollen gel incorporated with SWCNTs.…”

“…In previously reported LCE composite films, hetero polymer networks were utilized as the frame to form the alignment of liquid crystalline units, or as reinforcement phase to accomplish good mechanical properties [21,22]. Leveraging this approach, incorporating hetero skeleton structures can be an effective way of developing bulk LCE materials.…”

“…changes [4][5][6][7][8]. Owing to their characteristics as soft materials, currently, LCE materials have always been made in the forms with thin thickness, such as films [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], fibers [25][26][27][28] or applied as surface coating [29]. However, materials with thin thickness have limitations in forming mechanical actuators, and many actuation functions need to be realized using thick materials, such as bulk materials.…”

Study on the Optical and Mesomorphic Properties of Cholesteric Side-Chain Liquid Crystalline Elastomers Containing a Nematic Cross-Linking Agent

“…The lightly cross-linked network structures of LCEs can be obtained by copolymerization of different LC mesogens with various cross-linking agents. The different LC mesogens and cross-linking segments in LCE systems can result in materials with a variety of mesophases and distinct properties [12][13][14][15] , which make them promising for applications in actuators, photonics, and shape-memory materials [16][17][18][19][20][21] .…”

“…The lightly cross-linked network structures of LCEs can be obtained by copolymerization of different LC mesogens with various cross-linking agents. The different LC mesogens and cross-linking segments in LCE systems can result in materials with a variety of mesophases and distinct properties [12][13][14][15] , which make them promising for applications in actuators, photonics, and shape-memory materials [16][17][18][19][20][21] .Among the various mesophases of LCEs, the study of cholesteric LCEs is one of the most important and complex topics due to their special piezoelectricity, tunable mirrorless lasing, and photonics besides conventional properties of the cholesteric mesophase [22][23][24][25][26][27][28] . Correspondingly, they have the potential to act as nonlinear optical materials, electro-optical materials and the novel piezoelectric device.…”