Superlattice Structures of Plant-sourced Nanomaterials Hybridized with Inorganic thin films for Thermoelectric Materials

Concerns about energy security and strong dependency on fossil-sourced raw materials are heavily boosting the industry transition towards the utilization of renewable resources. Potential of plantderived nanoscale cellulosic materials have been successfully demonstrated in diverse applications.1 When the peculiar features of nanocellulosic materials are coupled with the numerous functionalisation opportunities achieved via e.g. hybridization, completely new application areas such as optical materials, nanoelectronics and (bio)sensors can be anticipated for these abundant biomaterial structures. This presentation shows how inherent features of cellulose, namely low thermal conductivity and high thermal stability can be exploited as a phonon blocking material in thermoelectric superlattice structures once hybridized with electrically conductive inorganic oxide layers. Superlattice structures with alternating layers of various nanocellulosic materials and ZnO showed that resistivity and thermal conductivity of such structures can be manipulated by the cellulosic thin layer nanoarchitecture. Only a submonolayer of CNF is needed to suppress the thermal conductivity of ZnO.2 Inorganic multilayer structures comprising stacks of SiO2/Al2O3 deposited on CNF film (individual layer thickness of 3.7 nm for SiO2 and 2.6 nm for and Al2O3) efficiently blocked the diffusion of the oxygen molecules through the CNF film structure.3 Moreover, simultaneously developed low temperature ALD processes enabled the inorganic thin film depositions on thermally sensitive biomaterials.