US Patent 7332857 Light emitting device and manufacturing method thereof

A region in which the concentration of a first organic compound and the concentration of a second organic compound change gradually (namely, a concentration change region 204b) exists within an organic compound film, and therefore a clear organic boundary does not exist. However, a region in which the first organic compound is capable of expressing its function (a first functional region) and a region in which the second organic compound is capable of expressing its function (a second functional region) exist, and therefore the function of each material can be expressed.