In 1821, T.J. Seebeck discovered the Seebeck effect when he noticed that a compass needle was deflected when a metal was heated with a heat gradient. He called the effect thermomagnetism. Oersted later redefined it when he observed that an electric current could produce a magnetic field and gave it the correct name of thermoelectricity. Thermoelectric devices can convert electrical energy into a temperature gradient. The application of this cooling or heating effect remained minimal until the development of semiconductor materials. With the advent of semiconductor materials came the capability for various practical thermoelectric refrigeration methods. When discussing thermoelectric applications, it is important to mention that most applications involve a thermoelectric module. This module could be a small or large device that has thermoelectric elements and contains two different types of thermoelectric materials. One material is n-type, and the other is p-type, often called a "uncouple." One uncouple shown in Fig. 1.3. A module consists of alternating n- and p-type thermoelectric elements. The combination of both carrier-type semiconductors means that the heat is carried in one direction only due to each material having a different free electron density at the same local temperature. These modules usually have a symmetrical number of each carrier type. The change in temperature between n- and p-type occurs when the current moves to a different carrier type. Current transferring to the n-type material causes the material to be heated since the n-type material has excess electrons. When the current transfers to the p-type material, the semiconductor without free electrons is cooled; these changing temperatures cause the module's cold side to be colder and the hot side to be hotter. If you are looking for high quality, high purity, and cost-effective Bismuth telluride, or if you require the latest price of Bismuth telluride, please feel free to email contact mis-asia.