Electrochemical deposition and thermoelectric characterisation of a semiconducting 2-D metal-organic framework thin film

Resumen del trabajo presentado en el Virtual Conference on Thermoelectrics (VCT), celebrado online del 21 al 23 de julio de 2020Conductive metal organic frameworks (c-MOFs) are hybrid materials composed of inorganic and organic building blocks, in which metal nodes are coordinated to highly conjugated organic linkers. The overlap between the metal and ligand frontier orbitals facilitates the charge transport in these materials. Porosity and heterogeneity in atomic species and linkers are features that have led to a predictably low thermal conductivity making c-MOFs potential candidates for thermoelectric generators (TEG). To implement their practical use, the synthesis and study of ultrathin c-MOFs nanosheets have recently been reported; however, the processing at large scale of these materials is still a challenge. In this work we present an electrochemical approach to the growth of conducting thin films of the 2D c-MOF Cu3(HHTP)2 (where HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene). Bulk Cu3(HHTP)2 was synthesized solvothermally according to the literature and we have subsequently fabricated thin films of this important framework by anodic electrochemical synthesis. We report the first thermoelectric measurements of this framework both in bulk and thin film form which resulted in Seebeck coefficients of -7.24 μV/K and -121.4 μV/K with a power factor of 3.15 x 10-3 μW/m for the film respectively. The study of conducting MOFs and their performance as TEG is expected to expand and offer alternatives to non-toxic, scalable and high-efficiency novel TEG materials.Peer reviewe