Organic-SnSe Hybrid Superlattice toward Synergistic Electrical Transport Optimization and Thermal Conductance Suppression.

Recently, layered SnSe has drawn broad research interest as a promising thermoelectric material that possesses great potential for application in energy conversion. However, extensive efforts have been devoted to optimizing the thermoelectric performance of SnSe, but the value is still far from satisfactory. Therefore, we developed an organic-inorganic superlattice hybrid by intercalating organic cations into SnSe interlayers in an attempt to enhance the thermoelectric properties. Organic intercalants can enlarge the basal spacing and decouple the SnSe layers, bringing about synergistic electrical transport modification and phonon softening. Thus, by simultaneously improving the electrical conductivity and reducing the thermal conductivity, a value of 0.34 is achieved at 342 K in tetrabutylammonium-intercalated SnSe, approximately two orders of magnitude higher than that of pristine SnSe single crystals. In addition, by opening van der Waals gaps via organic cations, outstanding flexibility of organic-intercalated SnSe is realized, with a superior figure of merit for flexibility of approximately 0.068. This work demonstrates a general and facile strategy to fabricate organic-inorganic superlattice hybrids with a considerable improvement in the thermoelectric performance via organic cation intercalation, which is promising for flexible thermoelectrics.