Thermoelectric devices are semiconductor heat or refrigeration units which use the Peltier effect to create a heat flux between the two surfaces of the module. TEC modules use two thin ceramic wafer with a series of P and N doped bismuth-telluride semiconductor material elements sandwiched between them. The ceramic material on both sides of the module adds rigidity and the necessary electrical insulation. The N element type material has an excess of electrons, while the P element type material has a deficit of electrons. One P element and one N element make up a couple junction that creates the thermoelectric effect.
When a DC current is applied to the circuit, a thermoelectric module can work as a cooler or heater depending on the direction of current. A thermoelectric cooler (TEC), or solid state heat pump, transfers heat from one side of the device to the other side against the temperature gradient.
There are many products using thermoelectric coolers, including small refrigeration systems, CCD cameras, laser diodes, and portable picnic coolers. In addition to the aforementioned, they are also used in thermal management of electronic devices, such as microprocessors, memory modules, etc.