Georgi Nadjakov discovered permanent internal photo-polarization in 1937. He made a electret with light and electricity. The new electret was called photo-electret. The previous type of electret, obtained by heat and electricity, were called by him thermoelectret.

 

Discovering the photoelectret state was the most considerable result of Georgi Nadjakov. It was formally recognized in Bulgaria after his death.

Back	Created: 10 December 2004 Updated: 29 March 2023