Electroluminescent elements and a method for their manufacture

An electroluminescent element comprising:

• a light emitting layer comprised of a mixture of a fluorescent first compound and a second compound which absorbs the fluorescence emitted by said first compound and emits fluorescence of longer wavelength than said fluorescence which is arranged between an anode and a cathode, and in which the concentration of said second compound with respect to the first compound in said light emitting layer is set so as to change with a gradient along the thickness direction of said light emitting layer.

A method for the manufacture of electroluminescent elements comprising the steps of:

• sandwiching a light emitting layer between an anode and a cathode which is provided with a process in which a transparent anode is formed on a transparent substrate, a process whereby a hole injection transport layer is formed using a mixture of a compound which has a charge injection/transportation capacity in a second compound which absorbs the fluorescence emitted by a fluorescent first compound and emits fluorescence of a longer wavelength that said fluorescence, a process whereby said first compound is formed into a film on the whole surface of said hole injection transport layer using a solvent of which the compatibilities with respect to said first compound and said second compound are controlled and said second compound in said hole injection transport layer is caused to permeate into said first compound layer, and a process whereby a cathode layer is formed over said light emitting layer.

The method for the manufacture of electroluminescent elements comprising the steps of:

• sandwiching a light emitting layer between an anode and a cathode which is provided with a process whereby a transparent anode is formed on a transparent substrate, a process whereby a fluorescent first compound is formed into a film on the whole surface, a process whereby a second compound which absorbs the fluorescence generated by said first compound and emits a fluorescence of longer wavelength that said fluorescence is applied as a solution and said second compound is caused to permeate into said first compound and a light emitting layer is formed, and a process whereby a cathode layer is formed over said light emitting layer.

A method for the manufacture of an electroluminescent elements comprising the steps of:

• sandwiching a light emitting layer between an anode and a cathode which is provided with a process whereby a transparent anode is formed on a transparent substrate, a process whereby a second compound which absorbs the fluorescence emitted by a first compound and emits fluorescence of a longer wavelength than said fluorescence is applied as a solution, a process whereby a film of said first compound is formed on the whole surface using a solvent of which the compatibilities in respect of said first compound and said second compound are controlled and a light emitting layer wherein the second compound has permeated into said first compound is formed, and a process whereby a cathode layer is formed over said light emitting layer.

The method for the manufacture of electroluminescent elements comprising the steps of:

• sandwiching a light emitting layer is sandwiched between an anode and a cathode which is provided with a process whereby a transparent anode is formed on a transparent substrate, a process whereby a light emitting layer is formed by mixing a fluorescent first compound and a second compound which absorbs the fluorescence emitted by a first compound and emits fluorescence of a longer wavelength than said fluorescence and applying the mixture as a solution, and a process whereby a cathode layer is formed over said light emitting layer.

The method for the manufacture of electroluminescent elements comprising the steps of:

• sandwiching a light emitting layer between an anode and a cathode which is provided with a process whereby a transparent anode is formed on a transparent substrate, a process whereby a light emitting layer is formed by attaching a fluorescent first compound as a solution, and a process whereby a cathode layer is formed over said light emitting layer.