Thermoelectric materials, thermoelectric module including thermoelectric materials, and thermoelectric apparatus including thermoelectric modules

A thermoelectric material represented by Formula 1, comprising a layered structure having a disordered structure in an in-plane direction:

• RaTbX2-nYn (1)
• wherein R is a rare earth element,
• T comprises at least one element selected from the group consisting of Group 1 elements, Group 2 elements, and a transition metal,
• X comprises at least one element selected from the group consisting of S, Se, and Te,
• Y is different from X and comprises at least one element selected from the group consisting of S, Se, Te, P, As, Sb, Bi, C, Si, Ge, Sn, B, Al, Ga and In,
• a is greater than 0 and less than or equal to 1,
• b is greater than or equal to 0 and less than 1, and
• n is greater than or equal to 0 and less than 2,
• wherein the thermoelectric material having a layered structure comprises a first layer comprising X, or X and Y;
• and a second layer comprising X and R, or X and Y and R, and
• wherein the first layer and the second layer are alternately arranged and T is intercalated between the first layer and the second layer.