Thermal to electric conversion with diodes

[Stanley514]

There is well known phenomenon such as thermal current in diodes which is 26millivolts at room temperature.And it increases with temperature rise.How good are diodes in converting heat to electricity and what qualities should have diode for perfect heat to electricity conversion?I read that scientists have experimented with quantum tunneling diodes for this purpose and claimed to achieve some results.
But do they really need quantum tunneling effects?It seems to me that usual solar cells convert light into electricity in similar way and there is no need for quantum
effects.Diodes in solar cells look quite efficient and don't seem to be a serious limitation.

 

[Naty1]

what "well known phenomena" are you referring to...thermal noise? other electrical components exhibit that...like resistors, capacitors,etc.