Organic-component dependent thermal conductivity reduction in ALD/MLD grown ZnO:organic superlattice thin films

Abstract

Inorganic–organic superlattice (SL) thin films are intriguing candidates for flexible thermoelectric applications; in such SLs, the heat conduction can be efficiently blocked at the inorganic/organic interfaces. Fabrication of these materials using the atomic/molecular layer deposition (ALD/MLD) technique allows precise layer-sequence manipulation. Another unique advantage of ALD/MLD is its capability to yield conformal coatings even on demanding substrates such as textiles. These benefits have been demonstrated in previous works for SL thin films where ZnO serves as the inorganic matrix and hydroquinone as the organic component. In this work, we extend the study to three other organic components, i.e., p-phenylenediamine, terephthalic acid, and 4,4′-oxydianiline, to address the importance of the bonding structure and the density difference at the inorganic/organic interface, and the thickness of the monomolecular organic blocking layer.