Symmetric strain fields as diffusion barrier: A new avenue to achieve diffusion-resistant, thermally stable thermoelectric interfaces

Elemental diffusion and reactions at interfaces significantly increase resistivity and reduce stability, particularly in thermoelectric (TE) systems containing highly diffusive elements like Te. Using thermodynamically stable phases as contact layers have eliminated interfacial reactions but have not been able to completely stop elemental diffusion. This work introduces an innovative approach to effectively increase the activation energy of cross-interface atom diffusion by creating a continuously interfacial symmetric strain field via a high density of interfacial edge dislocations. Specifically, a dense interfacial strain barrier layer is constructed using Ni 0.5 Te as contact layer, resulting in an atomically continuous Te 0.985 Sb 0.015 /Ni 0.5 Te interface. This design achieves a notable reduction in contact resistivity to 9 μΩ cm 2 while maintaining more than 75 % of the theoretical device efficiency at a hot-end temperature, ( T h ) of 523 K even after 21,600 min of aging. This method of optimizing both the interfacial microstructure and chemical composition provides a new avenue for constructing stably high-performance heterostructure devices.