Do you know thermoelectric coolers? They are also called Peltier coolers or TEC.

They are solid-state heat pumps that utilize the peltier effect.

During operation, DC current flows through the TEC, resulting in heat being transferred from one side of the TEC to the other, creating a cold side and a hot side. A single-state TEC can achieve temperature differences upto 70℃ , or can transfer heat at a rate of 138W. To achieve greater temperature differences(up to 131℃), select a multistage(cascade) TEC. To increase the amount of heat transferred, the TEC''''''''s module allows the use of multiple TECs mounted side by side.Have a look at some pictures.

And do you know what makes up of the TEC? That is semiconductor crystalbar and ceramic substrate. The elements in the picture above have two kinds, one is "N", the other is "P".

If you are interested in it, inquire me, i will be glad to answer you.

Have a nice day!