Tuning the shape and thermoelectric property of PbTe nanocrystals by bismuth doping

We report the synthesis of a series of monodispersed Bi-doped PbTe nanocrystals with tunable morphologies by using a doping precursor of bismuth(iii) 2-ethylhexanoate. The as-synthesized Pb_1-xBi _xTe (x = 0.005, 0.010, 0.015, 0.020) nanocrystals are characterized by X-ray diffraction, X-ray photoelectron spectroscopy and Hall measurements. The nanocrystals with controlled spherical, cuboctahedral, and cubic shapes were readily prepared by varying the Bi doping concentration. Thermoelectric investigation of these nanocrystals shows that the Bi³⁺ doping increases electrical conductivity from 350 to 650 K and changes the Seebeck coefficient sign from positive to negative.