Quasi Fermi level
A quasi Fermi level is a term used in quantum mechanics and especially in solid state physics for the Fermi level (chemical potential of electrons) that describes the population of electrons separately in the conduction band and valence band, when their populations are displaced from equilibrium. This displacement could be caused by the application of an external voltage, or by exposure to light of energy E > E g {\displaystyle E>E_{g}} , which alter the populations of electrons in the conduction band and valence band.