Embedded in-situ nanodomains from chemical composition fluctuation in thermoelectric A2Cu3In3Te8 (A = Zn, Cd)

Abstract Complex diamond-like chalcogenides, A2Cu3In3Te8 (A = Zn, Cd, Mn, Mg), were discovered and demonstrated to be promising thermoelectric materials in our prior work. Here we disclose that in-situ nanodomains coherently embedded in the A2Cu3In3Te8 (A = Zn, Cd) matrixes are generated by the chemical composition fluctuation. Cations enter into the interstitial lattice sites to form in-situ nanodomains, which slightly influence electron migration but effectively scatter phonons. The nanodomains can be successfully tailored by further composition fluctuation with the substitution of Cu+ for A2+, resulting in significantly improved electrical transport properties and reduced lattice thermal conductivity. The peak zT values of ∼1.0 and 1.2 at 873 K are achieved for Zn1.6Cu3.4In3Te8 and Cd1.6Cu3.4In3Te8, respectively, exceeding the hitherto reported zT values among quaternary diamond-like chalcogenides. Manipulating in-situ nanodomains in A2Cu3In3Te8 by introducing chemical composition fluctuation renders a promise in enhancing thermoelectric efficiency by nanostructure engineering within the complex thermoelectric materials.