Modulation of interface states at Fe/Al interface for thermoelectric module applications

Metal/metal interfaces play a crucial role in the practical applications of common metallic thermoelectric modules (TEMs), which economically convert heat to electricity in an environmentally friendly manner. The effect of modulation of Fe/Al interface states, introduced by the application of large bias currents, on the thermoelectric properties of the Fe/Al-based TEMs was investigated. The Seebeck coefficients of TEMs after applying bias currents in the Fe → Al and Al → Fe directions increased from 2.1 and 2.5 to 2.5 and 2.9 μV K−1, respectively, with prolonged applying them. The densities of Fe/Al interface states, calculated based on the capacitance– and conductance–frequency characteristics of the only Fe/Al interfacial samples, decreased from 2.6 × 1014 to 1.8 × 1011 cm−2 eV−1 with prolonged applying the bias currents. These results indicate that the TEMs’ Seebeck coefficients and the densities of Fe/Al interface states were negatively correlated. To enhance Seebeck coefficients, reductions in densities of interface states between dissimilar metals provide an alternative strategy for designing high-performance metallic TEMs.