Assembly-Driven Design of Nanocellulose-Based Thermoelectric Materials: Bridging Sustainable Building Blocks and Energy Conversion

Thermoelectric materials convert heat directly into electricity, providing a solution for energy harvesting and self-powered systems. Despite the progress, challenges remain in balancing efficiency, flexibility, and stability for practical applications. Nanocellulose offers a versatile platform with a high aspect ratio, mechanical robustness, and tunable surface chemistry. This account highlights how assembly strategies translate these properties into functional materials for energy conversion. By integrating top-down processing, bottom-up macroscopic/microscopic assembly, and molecular-level modification, hierarchical interfaces and structures can be engineered to optimize phonon scattering, carrier transport, and mechanical strength. Such control enables flexible, conformal, and stretchable devices for wearable electronics, solar-thermoelectric generators, radiative cooling, and multifunctional self-powered sensors. We examine how different assembly approaches shape morphology and interfaces, directly linking the structural design to device function. This framework emphasizes scalable and sustainable strategies for nanocellulose-based thermoelectrics, guiding the development of efficient, flexible, and environmentally friendly energy harvesting systems from fundamental research to practical applications.