Liquid-Crystal-Based Porous Metamaterials for Solar Thermal Energy Harnessing

Although the total solar energy incident on Earth exceeds human energy consumption by more than four orders of magnitude, limitations in our ability to efficiently harvest, store and convert this energy have contributed to a reliance on fossil fuels. For example, the building sector accounts for approximately 40% of global energy consumption, much of which is expended on heating and cooling [1,2] due to the limited ability of conventional buildings to passively maintain comfortable indoor temperatures. This lecture will discuss how lyotropic liquid crystals (LCs) can template mesoporous transparent cellulose based aerogels [2] and optically clear heat insulators (MOCHIs) [1], shaped as square-meter-scale films and multi-inch-thick slabs made from porous networks of nanotubes. A cost-effective solution-based process drives the self-assembly of nanometer-thin polysiloxane nanotubes around cylindrical surfactant micelles, forming LC gel networks. Replacing surfactants and solvents with air yields aerogel-like lightweight materials with >99% visible-range light transmittance and ~10 mWm^-1K^-1 thermal conductivity, much lower than that of still air. MOCHIs act as thermal barriers in wall-grade insulated window units and retrofit applications, while also enabling unconcentrated solar thermal energy harvesting and efficient long-term storage. Together, these capabilities open a potential pathway for transforming inefficient building envelopes into energy-generating, self-sustaining systems [1]. Beyond building-scale applications, the LC nanotemplating approach may offer pathways for addressing broader energy challenges, including mitigating the Earth’s energy imbalance. Similar strategies could enable the engineering of Earth-like miniature habitats on extraterrestrial bodies.

1. A. Bhardwaj, B. Fleury, B. Senyuk, E. Abraham, J.B. ten Hove, T. Lee, V. Cherpak & I. I. Smalyukh. Science 30, 1171-1176 (2025).

2. E. Abraham, B. Senyuk, T. Lee, J.B. ten Hove, Q. Liu & I.I. Smalyukh. Nat. Energy 8, 381–396 (2023).