TECHNOLOGY FOCUS - ELECTRONICS - Preferred Element: In the thermoelectric element, the thermoelectric semiconductor forms a matrix, and the nanosheet is dispersed in the matrix. In the thermoelectric element, the nanosheet is disposed on a grain boundary of the thermoelectric semiconductor.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The distance between layers of the layered structure is 1-40 angstroms. The average area of the nanosheet is 0.0001-100 square micrometers. The nanosheet comprises a layered material containing a metal hydroxide. The nanosheet comprises a layered double hydroxide of formula (M2+1-xM'3+x(OH)2)(A(n-)x/n.mH2O) (I). The thermoelectric semiconductor comprises an element selected from a transition metal, a rare earth element, a Group 13 element, a Group 14 element, a Group 15 element, and/or Group 16 element. The thermoelectric semiconductor comprises a thermoelectric semiconductor selected from a Bi-Te-containing material, a Co-Sb-containing material, a Pb-Te-containing material, a Ge-Tb-containing material, a Si-Ge-containing material, a Sb-Te-containing material, a Sm-Co-containing material, and/or transition metal silicide-containing material. The average particle diameter of the thermoelectric semiconductor is 0.01-100 micrometers. The thickness of the metal hydroxide is 0.1-50 nanometers.M2+=a divalent metal ion (preferably Mg2+, Ca2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, and/or Ga2+);M'3+=a trivalent metal ion (preferably Al3+, Cr3+, Mn3+, Fe3+, Co3+, Ni3+, and/or La3+);A(n-)=anion having a valence of n (preferably CO32-, OH-, NO3-, SO42-, ClO4-, and/or WO42-);x=0.2-0.33;n=1-3;m=0.5-4. EXAMPLE - Preparation of thermoelectric material (test) with P-type Bi0.5Sb1.5Te3 was carried out as follows: a Bi-Te-containing alloy was prepared to be used as particles of a thermoelectric semiconductor. In order to prepare the Bi-Te-containing alloy, Bi, Sb, and Te, which were raw materials, were weighed at a molar ratio of 0.5:1.5:3 and put together with a steel ball into a jar formed of sintered carbide, and the jar was rotated to prepare p-type Bi0.5Sb1.5Te3 powder. The Bi0.5Sb1.5Te3 powder was sorted to provide a powder having a size less than or equal to several tens of mu m by using a mechanical sieve (325 meshes) to obtain initial powder. Nanosheet powder was obtained by exfoliating Mg-Al LDH (formula: (Mg0.65Al0.33(OH)2)((CO3)0.17.0.5H2O)) in formamide, and washing and thermal-treating the resultant in the air. For uniform exfoliation, 0.05 g of LDH powder was put into and sealed in 100 cubic centimeters (cc) of formamide and was stirred for 24 hours at a speed of 170 revolutions per minute (rpm) while continuously pursing nitrogen. The formamide solution in which the exfoliated nanosheet was dispersed, was washed with 100 cc of ethanol four times and thermal-treated at 300 degrees C to obtain a dried nanosheet powder. The thickness of the nanosheet was less than or equal to several nm. The nanosheet powder was added to three 10 g samples of the Bi0.5Sb1.5Te3 powder such that the amounts of nanosheet were 0.5 wt.%, 0.25 wt.%, and 0.1 wt.%, respectively, and each of the three samples was mixed for 10 minutes using a high energy ball mill. In order to prevent oxidation of the thermoelectric material due to heat generated during ball milling, nitrogen was injected into the high energy ball mill. Mixed powders obtained as such were put into an alumina crucible and thermally-treated for 3 hours by increasing a temperature to 300 degrees C under a nitrogen and hydrogen mixture (N2 95 volume% and H2 5 volume%), thereby obtaining three samples of the thermoelectric material in which the amounts of the nanosheet were respectively 0.5 wt.%, 0.25 wt.%, and 0.1 wt.%. A Bi-Te-containing alloy that did not include a nanosheet was prepared as control material. The test/control material was evaluated for thermoelectric performance. It was found that, in test material the Seebeck coefficients increased and the thermal conductivities in a room temperature region were decreased as compared to control thereby improving thermoelectric performance of test as compared to control.