The invention discloses a preparation method of a
bismuth telluride based N type thermoelectric material Bi2(Te<1-x>Se<x>)3. A
melt mixing step and a
zone melting step are used for synthesis. The synthesis method comprises that single-substance raw materials can be selected and weighed according to a
chemical formula Bi2(Te<1-x>Se<x>)3 in which x is greater than or equivalent to 0.02 and lower than or equivalent to 0.1,
metal antimony (Sb) in the weight percentage of 0.01% to 0.03% and
nonmetal iodine (I) in the weight percentage of 0.03% to 0.06% are added on the basis of the weight obtained by weighing, and the purities of all the single-substance raw materials are greater than 4N; the materials are filled into a
quartz tube whose bottom is relatively flat by
sintering to implement vacuum-pumped tube sealing, and then filled into a rocking furnace of resistance heating, and the
quartz tube is placed in a vertical position and then sintered by
melt mixing synthesis. The
quartz tube is cooled naturally to the
room temperature after
sintering, and then removed and placed in a
melting furnace in a vertical zone for pulse
zone melting. The
bismuth telluride based N type thermoelectric material and the preparation method thereof have the advantages that the preparation method is simple, a high-density body material of a monocrystalline similar structure and including a few of inlaid nanometer
crystal grains can be obtained, via measurement, the ZT value of the thermoelectric material Bi2(Te<1-x>Se<x>)3 can reach 1.33 during 340K, and the material can be applied to fields including
waste heat recovery and
space exploration.