Is it real? how does it work?
You always need a heat difference - a warm area and a cold area. Photovoltaic cells do that in an indirect way (via light from the hot sun). Thermoelectric generators are a direct way to generate electricity from heat differences, but they don't need semiconductors.
According to precise usage in English-language textbooks, "heat" = "energy transferred because of a difference in temperature between two objects." Therefore in the OP's statement, "heat" is appropriate. "Heat difference" doesn't make sense here.
(However, even many physicists get sloppy with this terminology sometimes. :uhh:)
"More recent devices use semiconductor p–n junctions made from bismuth telluride (Bi2Te3), lead telluride (PbTe)"
Wait you said that they don't need semi-conductors right?Then whats this?
You can use them, you do not have to. That is an important difference.
@jtbell: Oh, sorry. In German, you can describe both with "Wärme", I didn't know that heat is energy transfer only in English.
But what makes the electrons move from one side to another? I get that electrons get more active but what makes them move in one direction?
How much do you know about quantum mechanics and thermodynamics? Overview at Wikipedia
And we engineers ignore the difference completely, seeing it as trivial.
Well, I know the very basics of thermodynamics and I can understand how wave functions work.
Not in colloquial English, but in physics as jargon it has that specific meaning.
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