The nature of 2D:3D SnS:Bi2Te3 interface and its effect on enhanced electrical and thermoelectric properties

Abstract In the present study, the effect of 2D-3D interfaces has been investigated by incorporating different concentrations of SnS 2D layers up to 5% into the Bi2Te3 semiconducting matrix. The charge transport across the interface was explored by Kelvin probe force microscopy (KPFM) measurements which indicates a potential barrier of 130 mv at the SnS:Bi2Te3 interface in the nanocomposite samples. The enhancement in Seebeck coefficient (185 μV/K) SnS:Bi2Te3 nanocomposite samples as compared to the (135 μV/K) pristine Bi2Te3 can be attributed to active carrier filtering by the potential barrier formed at the heterointerfaces. All SnS:Bi2Te3 nanocomposite samples possess lower thermal conductivity compared to the pristine Bi2Te3 sample. The interface density and size of the SnS nanosheets observed to be the dominant factor in reducing thermal conductivity. The simultaneous enhancement in the Seebeck coefficient(160 μV/K) and reduction in the thermal conductivity value (0.68 W/mK) in 1% SnS:Bi2Te3 nanocomposite sample leads to the enhancement in the value of ZT = 0.84, which is higher than that of the pristine Bi2Te3 sample.