NOVELTY - Thermoelectric material (I) comprises metal compound (a).    USE - (I) is useful in a thermoelectric module and a thermoelectric device (all claimed), preferably the device is a thermoelectric cooling system or a thermoelectric power generation system.    ADVANTAGE - (I) has a large Seebeck coefficient, a high electrical conductivity, and a low thermal conductivity. (I) improves the thermal stability of a device, which does not produce vibration and noise and avoids the use of a separate condenser and refrigerant.    DETAILED DESCRIPTION - Thermoelectric material (I) comprises metal compound of formula ((R1-a-R1a)(T1-b-T1b)3 plus minus y) (a).    R, R1a = at least one element comprising a rare earth element or a transition metal;    T, T1a = at least one element comprising sulfur, selenium, tellurium, phosphorus, arsenic, antimony, bismuth, carbon, silicon, germanium, tin, boron, aluminum, gallium or indium;    a, b = 0-1;    y = 0 to less than 1.    INDEPENDENT CLAIMS are included for:    (1) a thermoelectric module comprising: a first electrode, a second electrode, and a thermoelectric element interposed between the first electrode and the second electrode, where the thermoelectric element comprises the thermoelectric material;    (2) a thermoelectric device comprising: a heat supply member; and a thermoelectric module comprising: a thermoelectric element which absorbs heat from the heat supply member, a first electrode contacting the thermoelectric element and a second electrode facing the first electrode and contacting the thermoelectric element, where the thermoelectric element comprises the thermoelectric material; and    (3) a method of manufacturing a thermoelectric material, comprising: combining a first material and a second material to form a combination; and heat treating the combination to form the thermoelectric material, where the first material comprises R and R1a, and each of R and R1a comprises at least one element comprising a rare-earth element and a transition metal; the second material comprises T and T1a, and each of T and T1a comprises at least one element comprising sulfur, selenium, tellurium, phosphorus, arsenic, antimony, bismuth, carbon, silicon, germanium, tin, boron, aluminum, gallium, and indium; and mole ratio of a sum of R and R1a to a sum of T and T1a is 1:2-1:4.    DESCRIPTION OF DRAWING(S) - The figure shows the schematic representation of a thermoelectric cooler.