Functional layer forming ink and self-luminous element manufacturing method
An ink used in forming a functional layer of a self-luminous element by a printing method, the ink including a functional material and a mixed solvent. The mixed solvent includes solvents each having different vapor pressures. The functional material is dissolved or dispersed in the mixed solvent. A solvent that has a lowest vapor pressure among the solvents has a viscosity of at least 53 mPa·s, and a viscosity of the mixed solvent is 15 mPa·s or less.
1. An ink used in forming a functional layer of a self-luminous element by a printing method, the ink comprising:
a functional material; and
a mixed solvent including solvents each having different vapor pressures, wherein
the functional material is dissolved or dispersed in the mixed solvent,
a solvent that has a lowest vapor pressure among the solvents has a viscosity of at least 53 mPa·s, and
a viscosity of the mixed solvent is 15 mPa·s or less.
2. The ink of claim 1 , wherein
the viscosity when 80% of the mixed solvent is evaporated is at least 32 mPa·s.
3. The ink of claim 1 , wherein
a solvent that has a highest vapor pressure among the solvents has a lowest viscosity among the solvents.
4. The ink of claim 1 , wherein
the functional material is a low molecular weight material.
5. A method of manufacturing a self-luminous element, the method comprising:
preparing a substrate;
forming a first electrode on or above the substrate;
forming a functional layer on or above the first electrode; and
forming a second electrode on or above the functional layer, wherein
the forming of the functional layer includes a printing process using a functional layer forming ink and a drying process of drying the functional layer forming ink, and
the functional layer forming ink includes a functional material dissolved or dispersed in a mixed solvent including solvents each having different vapor pressures, a solvent that has a lowest vapor pressure among the solvents having a viscosity of at least 53 mPa·s, and a viscosity of the mixed solvent being 15 mPa·s or less.
6. The method of claim 5 , wherein
the functional layer is a light-emitting layer or a charge transfer facilitating layer.
7. The method of claim 6 , wherein
the charge transfer facilitating layer is a layer having a hole injection property, or a hole transport property or both a hole injection and transport property, or an electron injection property, or an electron transport property, or both an electron injection and transport property.