Layered hybrid selenoantimonates with reduced thermal conductivity

Four ternary selenoantimonates, Ag₂SbSe₃(enH) (I), KCu₂SbSe₃ (II), Cu₂SbSe₃(pdaH ₂)_0.5 (III), and Cu₂SbSe₃(bdaH ₂)_0.5 (IV) (en = ethylenediamine, pda = propanediamine, bda = butanediamine) were synthesized by solvothermal reactions using amines as solvents. The structures consist of M/Sb (M = Cu, Ag) intermetallic layers connected by either protonated amines or potassium ions. The optical bandgaps of these compounds were estimated from their optical absorption spectra (Kubelka-Munk function) with the values ranging from 0.9 to 1.8 eV. Thermal conductivity measurements were carried out on I, III, and IV, as well as on related compounds Cu₂SbSe₃(en)_0.5 and Cu ₂SbSe₃(en). In comparison with the inorganic counterpart compound CuSbSe₂, the hybrid structures clearly show significantly reduced thermal conductivity, as a result of incorporation of inorganic-organic interface. The study demonstrates an effective approach to enhance the thermoelectric efficiency of such material systems.