Light-emitting device and electronic apparatus

• US 7,919,916 B2
• Filed: 08/18/2008
• Issued: 04/05/2011
• Est. Priority Date: 09/18/2007
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kobayashi, Hidekazu
• Primary Examiner(s): Won; Bumsuk
• Assistant Examiner(s): Breval; Elmito
• Application Number:
  US12/193,276
• Publication Number:
  US 20090072709A1
• Time in Patent Office: 960 Days
• Field of Search: 313495-512, 315/169.3, 315/169.4, 257/40, 257/79, 428/690, 428/917, 345/30, 345/36, 345/44, 345/45
• US Class Current: 313/503
• CPC Class Codes: H10K 50/852 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: H10K 50/86 Arrangements for improving contrast, e.g. preventing reflection of ambient light
• CPC Class Codes: H10K 59/30 Devices specially adapted for multicolour light emission
• CPC Class Codes: H10K 59/35 comprising red-green-blue [RGB] subpixels

Abstract

A light-emitting device includes a light-emitting element having a first electrode layer, a second electrode, a light-emitting functional layer, a reflective layer which reflects light toward the light-emitting functional layer, a translucent semi-reflective layer which reflects some portion of light emitted from the light-emitting functional layer and transmits the rest of light therethrough, and a color filter which transmits light which passed through out the translucent reflective layer. An optical path d₁ has a value between d_1a calculated by d_1a=(p+1/2)·λ/2−(φ₁−φ₂)·λ/4π−n_z·t_z and d_1b=m·λ/2+(φ₃+φ₂)·λ/4π.

Claims

1. A light-emitting device comprising:

a light-emitting element having a substrate, a first electrode layer, a translucent semi-reflective layer, and a light-emitting functional layer disposed between the first electrode and the translucent semi-reflective layer;

a reflective layer between the substrate and the first electrode; and

a color filter which is disposed at the opposite side of the light-emitting functional layer with the translucent semi-reflective layer therebetween and transmits light which passed through out the translucent reflective layer,

wherein an optical path d₁ which is a way from the reflective layer to the translucent semi-reflective layer is a value between d_1a calculated by expression 1 and d_1b calculated by expression 2,

wherein d_1a=(p+1/2)·

λ

/2−

(φ

₁−

φ

₂)·

λ

/4π

−

n_z·

t_z (expression

     1), and d_1b=m·

λ

/2+(φ

₃+φ

₂)·

λ

/4π

(Expression

     2), wherein λ

is a wavelength at a peak transmittance of the color filter, φ

₁ is a phase change when light of a wavelength λ

, which advances toward the translucent semi-reflective layer from the opposite side of the light-emitting functional layer, reflects from an interface of the translucent semi-reflective layer, which is at the opposite side of the light-emitting functional layer, φ

₂ is a phase change when the light of a wavelength λ

, which advances toward the reflective layer from the light-emitting functional layer, reflects from the reflective layer, and φ

₃ is a phase change when the light of a wavelength λ

, which advances toward the translucent semi-reflective layer from the light-emitting functional layer, reflects from the interface of the translucent semi-reflective layer which is at the opposite side of light-emitting functional layer side wherein p is a positive integer, m is a positive integer, n_z is a reflectance of the translucent semi-reflective layer with respect to the light of a wavelength λ and

t_z is a thickness of the translucent semi-reflective layer.

2. The light-emitting device according to claim 1, wherein the translucent semi-reflective layer serves as a second electrode opposite from the first electrode with the light-emitting functional layer disposed therebetween.

3. The light-emitting device according to claim 1, further comprising a second electrode between the translucent semi-reflective layer and the light-emitting functional layer.

4. The light-emitting device according to claim 1, wherein the optical path d₁, which is a way from the reflective layer to the translucent semi-reflective layer, is an average value of d_1a calculated by the expression 1 and d_1b calculated by the expression 2.

5. The light-emitting device according to claim 1,

further comprising a plurality of light-emitting elements which allows different colors of light to pass through the translucent semi-reflective layer thereof;

and

a plurality of the color filters having different peak transmitting wavelengths λ

of light,

wherein each of the color filters is disposed to correspond to any of the plurality of light-emitting elements and constitutes one set of a color filter and a light-emitting element,

wherein in each set of a color filter and a light-emitting element, the optical path d₁, which is a way from the reflective layer to the translucent semi-reflective layer, is a value between d_1a calculated by the expression 1 and d_1b calculated by the expression 2.

6. An electronic apparatus comprising the light-emitting element according to claim 1.

7. The light-emitting device according to claim 1, wherein m has a value of 1.

8. The light-emitting device according to claim 1, wherein p has a value of 1.

9. The light-emitting device according to claim 1, wherein m and p each have a value of 1.