Georgi Nadjakov (also spelled Georgi Nadzhakov or Nadjakov; Georges Nadjakoff) (Bulgarian: Георги Наджаков) (26 December 1896 – 24 February 1981) was a Bulgarian physicist.

Sofia University sent him to specialize in the laboratories of Paul Langevin and Marie Curie in Paris, where he investigated photoelectricity for one year.

Georgi Nadjakov experimentally investigated photoconducting properties of sulphur.

He prepared the permanent photoelectret state of matter for the first time and published his paper in 1937 [1] and 1938.

Its practical application led to the invention of the photocopier by Chester Carlson some years later.