The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. The term "thermoelectric effect" encompasses three separately identified effects: the Seebeck effect, Peltier effect, and Thomson effect. The Seebeck effect generates an electromotive force, leading to the current equation:

$$J = \sigma \left( E - S \frac{\Delta T}{T} \right)$$

where $J$ is the current density, $\sigma$ is the electrical conductivity, $E$ is the electric field, $S$ is the Seebeck coefficient, $\Delta T$ is the temperature difference, and $T$ is the average temperature. The Peltier effect, on the other hand, describes the heating or cooling of a junction between two different conductors when a current flows through it. The Thomson effect describes the heating or cooling of a conductor when a current flows through it in the presence of a temperature gradient.

The thermoelectric effect is caused by charge carriers within the material (either electrons or places where an electron is missing, known as "holes") diffusing from the hotter side to the cooler side, similarly to the way gas expands when it is heated. The thermoelectric property of a material is measured in volts per Kelvin. The fundamental problem in creating efficient thermoelectric materials is that they need to be good at conducting electricity but poor at conducting heat.

Thermoelectric devices can be used to generate electricity, measure temperature, or change the temperature of objects. They can also be used as temperature controllers because the direction of heating and cooling is determined by the polarity of the applied voltage. Some applications of the thermoelectric effect include:

• Thermoelectric materials convert thermal energy into electrical energy, making them useful for power generation in remote locations or in space.
• Thermoelectric coolers are used in refrigeration and air conditioning systems[[5]](https://peakse...