Microlens for organic EL element, organic EL element using the same, and manufacturing methods thereof
A microlens for an organic EL element includes a cured resin layer having concavities and convexities formed on a surface thereof, wherein when a Fourier-transformed image is obtained by performing two-dimensional fast Fourier transform processing on a concavity and convexity analysis image obtained by analyzing a shape of the concavities and convexities by use of an atomic force microscope, the Fourier-transformed image shows a circular or annular pattern substantially centered at an origin at which an absolute value of wave number is 0 μm −1 , and the circular or annular pattern is present within a region where an absolute value of wave number is within a range of 1 μm −1 or less. The microlens is disposed on a light-emitting surface of the organic EL element.
1. A microlens for an organic EL element, which is used by being disposed on a light-emitting surface of the organic EL element, said microlens comprising
a cured resin layer having concavities and convexities formed on a surface thereof,
wherein a Fourier-transformed image of said concavities and convexities shows a circular or annular pattern substantially centered at an origin at which an absolute value of wave number is 0 μm −1 , and the circular or annular pattern is present within a region where an absolute value of wave number is within a range of 1 μm −1 or less, wherein said Fourier-transformed image is obtained by performing two-dimensional fast Fourier transform processing on a concavity and convexity analysis image, and said concavity and convexity analysis image is obtained by analyzing a shape of the concavities and convexities using an atomic force microscope, and
wherein, when intensities of emission spectra are measured at randomly selected measuring points on the surface on which the concavities and convexities are formed, wherein light incident on the surface of the cured resin layer on which said concavities and convexities are not formed exits from the surface of said cured resin layer on which the concavities and convexities are formed, said cured resin layer satisfies a condition represented by the following inequality (1):
Σ( y (θ)− y 0 (θ)) 2 ≦0.05 (1)
wherein
θ represents eight measuring angles of 0°, 10°, 20°, 30°, 40°, 50°, 60°, and 70°,
0° represents the measuring angle in a direction perpendicular to the surface of said cured resin layer,
y(θ) represents values obtained by normalizing measured values of intensities of emission spectra at the angles θ with respect to a measured value of an intensity of an emission spectrum at an angle of 0°, wherein the normalized theoretical value y(0) of the intensity spectrum at an angle of 0° is 1.0, and
y 0 (θ) represents values obtained by normalizing theoretical values, determined from a radiation pattern based on the Lambert law, of intensities of emission spectra at the angles θ with respect to a theoretical value, determined from the radiation pattern, of an intensity of an emission spectrum at an angle of 0°.
2. The microlens for an organic EL element according to claim 1 , wherein an average height of the concavities and convexities is 400 to 1,000 nm.
3. The microlens for an organic EL element according to claim 1 , wherein an average pitch of the concavities and convexities is within a range from 2 to 10 μm.
4. An organic EL element comprising:
a transparent supporting substrate;
a transparent electrode;
an organic layer; and
a metal electrode, wherein
the microlens for an organic EL element according to claim 1 is stacked on a light-emitting surface of the transparent supporting substrate.
5. The microlens according to claim 1 , wherein said cured resin layer is obtained by curing a curable resin layer wherein said curing is conducted at a temperature ranging from room temperature up to 250° C. for a curing time from 0.5 minutes to 3 hours.
6. The microlens according to claim 1 , wherein said cured resin layer was cured by irradiating a curable resin layer with ultraviolet light.
7. The microlens according to claim 1 , wherein said cured resin layer comprises a cured epoxy resin layer.
8. The microlens according to claim 1 , wherein said cured resin layer has a thickness of 1 to 500 μm.
9. The microlens according to claim 1 , wherein the average pitch of the concavities and convexities is within a range of 2.5 to 5 μm.
10. The microlens according to claim 1 , wherein the average height of the concavities and convexities is 600 to 1000 nm.
11. The microlens according to claim 1 , wherein the average height of the concavities and convexities is 700 to 900 nm.
12. The microlens according to claim 1 , wherein said cured resin layer has a thickness of 1 to 500 μm, the average height of the concavities and convexities is 400 to 900 nm, and the average pitch of the concavities and convexities is within a range of from 2 to 10 μm.
13. The microlens according to claim 1 , wherein said circular or annular pattern is formed by bright spots, and 50% or more of said bright spots are present within the region where an absolute value of wave number is within a range of 1 μm −1 .
14. The microlens according to claim 1 , wherein said circular or annular pattern is formed by bright spots, and 80% or more of said bright spots are present within the region where an absolute value of wave number is within a range of 1 μm −1 .
15. The microlens according to claim 1 , wherein said circular or annular pattern is formed by bright spots, and 90% or more of said bright spots are present within the region where an absolute value of wave number is within a range of 1 μm −1 .
16. The microlens according to claim 1 , wherein said fourier transformed image shows an annular pattern.
17. The microlens according to claim 1 , wherein said cured resin layer comprises a curable resin that has been cured wherein the curable resin is selected from the group consisting of epoxy resins, acrylic resins, urethane resins, melamine resins, urea resins, polyester resins, phenol resins, and cross-linking type liquid crystal resins.