Organic light-emitting element, image display device and production method thereof

An organic light-emitting element comprising an anode, a cathode and a light-emitting layer placed between the anode and cathode, the light-emitting layer comprising:

• a first mixed light emitting layer;
• a first mixed transport layer disposed on the first mixed light-emitting layer;
• a second mixed light-emitting layer disposed on the first mixed transport layer;
• a second mixed transport layer disposed on the second mixed light-emitting layer;
• and
• a third mixed light-emitting layer disposed on the second mixed transport layer,
• wherein:
• each of the mixed light-emitting layers is composed of a hole transport material, an electron transport material, and a dopant which determines a color of an emitted light, the first mixed light-emitting layer is closest to the anode side, and the third mixed light-emitting layer is closest to the cathode side,
• an electron mobility of the electron transport material at the third mixed light emitting layer is higher than a hole mobility of the hole transport material at the first mixed light-emitting layer,
• a dopant concentration of the third mixed light-emitting layer is higher than a dopant concentration of the first mixed light-emitting layer,
• the first mixed light-emitting layer and the first mixed transport layer include a common first hole transport material and a common first electron transport material,
• the second mixed light-emitting layer, the second mixed transport layer, and the third mixed light-emitting layer include a common second hole transport material and a common second electron transport material,
• the first mixed light-emitting layer emits a blue color, the second mixed light-emitting layer emits a green color, and the third mixed light-emitting layer emits a red color,
• the first hole transport material is different from the second hole transport material, the first electron transport material is different from the second electron transport material.