OLED device having improved light output

1. An organic light-emitting diode (OLED) device, comprising:

first and second non-metallic transparent electrodes, and one or more layers of organic material formed between the first and second non-metallic transparent electrodes, the one or more layers of organic material including one or more light-emitting layers that emit emitted light and that emit trapped light into the first and second non-metallic transparent electrodes and the one or more layers of organic material; and

a non-metallic reflective layer that reflects the emitted light located on a side of either of the first or second non-metallic transparent electrodes opposite to the one or more organic material layers;

wherein the device further comprises a non-metallic light transmissive scattering layer that scatters trapped light into emitted light, external to, and in optical contact, with the organic material layers and the electrodes or wherein the non-metallic reflective layer comprises a non-metallic reflective scattering layer that scatters trapped light into emitted light, external to, and in optical contact with, the one or more organic material layers and the electrodes;

a light-transmissive substrate through which the emitted light emitted by the one or more light-emitting layers is transmitted;

a low-index element having an optical refractive index lower than the optical refractive index of the light-transmissive substrate, the one or more light-emitting layers; and

wherein the low-index element is located between the light-transmissive substrate and the first and second non-metallic electrodes and between the light-transmissive substrate and the non-metallic light-transmissive scattering layer.

2. The OLED device of claim 1 , wherein the non-metallic reflective layer comprises a plurality of non-metallic layers with differing optical indices.

3. The OLED device of claim 1 , wherein the non-metallic reflective layers comprises a reflective scattering layer in optical contact with the one or more organic material layers and the electrodes.

4. The OLED device of claim 3 , wherein the non-metallic reflective scattering layer comprises scattering particles.

5. The OLED device of claim 4 , wherein the scattering particles are formed in a layer having two sides and comprising a matrix having an optical index lower than the optical index of the scattering particles, or wherein a layer having an optical index lower than the optical index of the scattering particles is coated over one side of a layer of scattering particles.

6. The OLED device of claim 3 , wherein the non-metallic reflective scattering layer has a light scattering surface.

7. The OLED device of claim 1 , wherein the first and/or second non-metallic transparent electrodes comprises a metal oxide.

8. The OLED device of claim 1 , wherein the one or more organic layers includes two or more light-emitting layers.

9. The OLED device of claim 1 , wherein the non-metallic reflective layers is co-extensive with the first or second transparent electrode.

10. The OLED device of claim 1 , wherein the non-metallic reflective layers reflects light over the visible spectrum.

11. The OLED device of claim 1 , wherein the non-metallic reflective layer preferentially reflects light of a given frequency range within the visible spectrum.

12. The OLED device of claim 11 , wherein the frequency range corresponds to red, green, blue, cyan, or yellow.

13. The OLED device of claim 1 , wherein the OLED device is a display device, an area illumination device, or a backlight.

14. The OLED device of claim 1 , further comprising a substrate, and wherein the non-metallic reflective layer is between the substrate and the non-metallic transparent electrodes and the one or more organic material layers.

15. The OLED device of claim 1 , wherein the non-metallic reflective layer comprises materials having a dielectric constant with a positive real part.

16. The OLED device of claim 1 , wherein the non-metallic reflective layer comprises materials that do not have free electrons in a conduction band.