Thermoelectric devices are semiconductor modules which use the Peltier Effect to create a heat flux between the junctions of two different types of materials. Named after French physicist Athanase Peltier, the Effect shows that a temperature differential is created when DC current is applied across two dissimilar materials. (It is one of the three thermoelectric effects; the others are the Seebeck Effect and Thomson Effect.)
A typical thermoelectric module is manufactured using two thin ceramic wafers with a series of N and P doped bismuth-telluride semiconductor material sandwiched between them. The ceramic material adds rigidity and the necessary electrical insulation. The N type material has excess electrons, while the P type material has a deficit of electrons. One N and one P make up a couple.
When a DC current is applied to the circuit, the thermoelectric module can work as a cooler or heater depending on the current’s direction. 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. Many products use thermoelectric coolers, including small refrigeration systems, CCD cameras, laser diodes and portable picnic coolers. They are also used in the thermal management of microprocessors, memory modules and other electronic devices.
Although a TEC provides a very simple and reliable solution for cooling devices, its poor thermal performance prevents its broader usage. Compared with traditional refrigeration systems, the coefficient of performance (COP) of a TEC is only about 1/5 that of a refrigeration system using a vapor compression cycle. Currently, the uses of TECs in electronics cooling are limited to systems that require temperature stability or sub-ambient operating conditions, or specially designed devices. Laser beam components and high energy optical modules are such examples.