Organic EL element, organic EL panel, and organic EL element manufacturing method
An organic EL element including an anode, a first functional layer including organic material, disposed above the anode, a second functional layer including organic material, disposed on and in contact with the first functional layer, a light emitting layer disposed on and in contact with the second functional layer, and a cathode disposed above the light emitting layer. A highest occupied molecular orbital (HOMO) level of the organic material of the second functional layer has an energy level at least 0.2 eV lower than that of a HOMO level of the organic material of the first functional layer, and film thickness of the second functional layer is 15 nm or less.
1. An organic electroluminescence (EL) element comprising:
an anode;
a first functional layer including an organic and polymeric material disposed above the anode;
a second functional layer including an organic and polymeric material disposed on and in contact with the first functional layer;
a light emitting layer disposed on and in contact with the second functional layer; and
a cathode disposed above the light emitting layer, wherein
a highest occupied molecular orbital (HOMO) level of the material of the second functional layer is lower than that of a HOMO level of the material of the first functional layer,
an energy gap between the first functional layer and the second functional layer is 0.2 eV or more, and
a film thickness of the second functional layer is 15 nm or less.
2. The organic EL element of claim 1 , wherein a hole mobility of the second functional layer is at least 1×10 −9 cm 2 /Vs.
3. The organic EL element of claim 1 , wherein an electron mobility in the light emitting layer is larger than a hole mobility in the light emitting layer.
4. The organic EL element of claim 1 , wherein an energy of singlet excitons in the material of the second functional layer is larger than an energy of singlet excitons in a functional material included in the light emitting layer.
5. The organic EL element of claim 1 , wherein an energy of triplet excitons in the material of the second functional layer is larger than an energy of triplet excitons in a functional material included in the light emitting layer.
6. The organic EL element of claim 1 , wherein
the anode is a light reflective electrode, and
a distance between a light emitting layer side surface of the anode and an anode side surface of the light emitting layer is 40 nm or less.
7. The organic EL element of claim 6 , wherein
an optical cavity structure including a light transmissive layer is formed between the light emitting layer side surface of the anode and a light emitting layer side surface of the cathode, and
the light transmissive layer includes indium tin oxide (ITO) or indium zinc oxide (IZO).
8. The organic EL element of claim 1 , wherein
the HOMO level of the material of the second functional layer has an energy level no more than 0.6 eV lower than that of the HOMO level of the material of the first functional layer, and
the film thickness of the second functional layer is 5 nm or more.
9. An organic electroluminescence (EL) display panel comprising:
a plurality of the organic EL element of claim 1 disposed on a substrate.