Patent ID: 7196360

Claim:
A light emitting device comprising an organic light emitting element, the organic light element having: an anode; a cathode; an organic compound film containing a hole transporting material and an electron transporting material; wherein the organic compound film has a structure comprising in a direction from the anode to the cathode: a hole transporting region comprising the hole transporting material; a first concentration change region in which the proportion of the electron transporting material increases gradually until a ratio between the hole transporting material and the electron transporting material becomes x:y (where x and y are positive constants); a mixture region containing the hole transporting material and the electron transporting material at the ratio of x:y; a second concentration change region in which the proportion of the electron transporting material gradually increases further from the x:y ratio; and an electron transporting region comprising the electron transporting material; and wherein a light emitting region, into which a light emitting material for performing light emission is added, is formed within the mixture region.