Fig. 2: Observation of defect-tolerant electron, but defect-sensitive heat transport in the temperature- and composition-dependent thermoelectric coefficients.
a–c Room temperature, in-plane thermal conductivities, Seebeck coefficients, and electrical conductivities of Cu-BHT films as a function of Cu/BHT ratio. In a our experimental thermal conductivity at the insulating state, i.e., lattice contribution at zero electrical conductivity, κσ=0 (blue dot line) is extracted from Supplementary Fig. 25. The error bars in Fig. 2b, c represent sample standard deviation. The data reported here are averaged over 90 devices for conductivities and 57 devices for Seebeck coefficient across 14 different batches of films. Among them, we only observed two devices showing negative Seebeck coefficient. d Diagrams illustrating the interplay between chemical and structural (im) perfections, coherent charge carrier and incoherent lattice vibrations, and electronic landscape. e, f Temperature-dependent in-plane thermal conductivities and Seebeck coefficients of different compositions. Since the Wiedemann-Franz law is found to be valid (Supplementary Fig. 25), in a, e the electronic and lattice contributions to the total thermal conductivities are evaluated from the Wiedemann-Franz law. The error bars for total thermal conductivity in Fig. 2a, e reflect 7% uncertainty associated with the repeatability of the measurements, mainly due to the variability in thermal contacts and the measurement accuracy of the equipment. Combined with the ~7% uncertainty arising from measurement accuracy for the determination of electronic contribution, the error bars for the lattice thermal conductivity in Fig. 2a, e are obtained in quadrature. g Temperature-dependent electrical conductivity as a function of Cu/BHT ratio, where a transition from thermal activation to metallic transport is seen within a narrow range of compositions (ratio 5–5.5). h, i Decomposition of the measured electrical conductivity of Cu/BHT ratio of 2 into contributions from intragrain metallic transport pathway and from disordered metallic and hopping transport pathways in the grain boundaries.
