Molecular Control of Charge Carrier and Seebeck Coefficient in Hybrid Two-Dimensional Nanoparticle Superlattices

The development of high efficiency thermoelectric materials would revolutionize energy harvesting capabilities, and be useful for a large number of applications. Hybrid organic-inorganic nanostructured materials are an intriguing platform for developing efficient thermoelectric systems due to the possibility of independently controlling the thermal and electrical conductivity of the material with intelligent choices for material components. In this study we control the thermopower of hybrid 2-dimensional (2D) nanoparticle-molecule superlattices by systematically modifying molecular properties. Five conjugated, ladder-type, heteroacene molecules are used to interlink gold nanoparticles, and control the thin-films’ properties. Interestingly, we measure a change in the sign of the Seebeck coefficient, corresponding to a crossover of the majority charge carrier (from hole to electron). Hall-effect measurements are used to confirm the change in dominant carrier for these systems. And density functional theory ...