Organic EL element and organic EL display panel
View Patent ↗An organic electroluminescence (EL) element that has an anode; a cathode; an organic light-emitting layer between the anode and the cathode that emits light according to recombination of holes injected from the anode and electrons injected from the cathode; and an electron transport layer between the cathode and the organic light-emitting layer that transports electrons from the cathode to the organic light-emitting layer. The electron transport layer includes an n-type dopant that includes an electron-donating substance, the electron transport layer being doped with the n-type dopant at a doping concentration that is higher than a doping concentration at which light emittance efficiency of the organic light-emitting layer is greatest.
1. An organic electroluminescence (EL) element comprising:
an anode;
a cathode;
an organic light-emitting layer between the anode and the cathode;
an electron transport layer between the cathode and the organic light-emitting layer; and
a sealing layer on an opposite side of the cathode from the electron transport layer, wherein
the electron transport layer comprises an n-type dopant that comprises an electron-donating substance, a normal region of the electron transport layer being doped with the n-type dopant at a doping concentration that is higher than a doping concentration at which light emittance efficiency of the organic light-emitting layer is greatest,
a crack is in the sealing layer, and
the electron transport layer has a graduated region in which the doping concentration of the n-type dopant gradually decreases, a lowest doping concentration in the graduated region being closest to the crack.
2. The organic EL element of claim 1 ,
wherein
the organic light-emitting layer has a region at which light emittance efficiency is greatest, in a region of the organic light-emitting layer corresponding to the graduated region.
3. The organic EL element of claim 1 , wherein
the n-type dopant is an alkali metal or alkaline earth metal.
4. The organic EL element of claim 1 , wherein
the n-type dopant is barium.
5. The organic EL element of claim 4 , wherein
the doping concentration of the barium is greater than 15 wt %.
6. The organic EL element of claim 4 , wherein
the doping concentration of the barium is greater than or equal to 25 wt %.
7. The organic EL element of claim 5 , wherein
the doping concentration of the barium is less than or equal to 50 wt %.
8. An organic EL display panel comprising:
the organic EL element of claim 1 .
9. The organic EL element of claim 1 , wherein
the graduated region is due to reaction with water or gas that enters via the crack.