Article comprising a microcavity light source
First Claim
1. An article comprising a layer structure on a major surface of a substrate body, said layer structure comprisinga) spaced apart first and second reflectors defining a microcavity of effective optical length L;
- b) at least one active layer that comprises organic material capable of electroluminescence, and having an electroluminescence spectrum including an emission region, with at least a portion of the active layer disposed between said reflector means; and
c) electrodes that facilitate flowing a current through the at least portion of the active layer such that the microcavity can be caused to emit radiation;
CHARACTERIZED IN THATd) the layer structure comprises at least a first and a second active layer, with at least a portion of each of said active layers disposed between said reflector means, and with said first and second active layers having a combined electroluminescence spectrum including an emission region; and
e) the effective optical length L is selected such that the microcavity is a multimode cavity that simultaneously supports at least two modes of radiation, each of said modes having a wavelength within said emission region of said combined electroluminescence spectrum, such that the microcavity can simultaneously emit radiation of at least two predetermined colors.
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Abstract
Optical microcavities are potentially useful as light emitters for, e.g., flat panel displays. Such microcavities comprise a layer structure, including two spaced apart reflectors that define the cavity, with a layer or layers of organic (electroluminescent) material disposed between the reflectors. We have discovered that a microcavity can simultaneously emit radiation of two or more predetermined colors such that the emission has a desired apparent color, exemplarily white. Emission of two or more colors requires that the effective optical length of the cavity is selected such that the cavity is a multimode cavity, with the wavelengths of two or more of the standing wave modes that are supported by the cavity lying within the emission region of the electroluminescence spectrum of the active material. A particular embodiment with two organic emitting (active) layers is disclosed.
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Citations
23 Claims
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1. An article comprising a layer structure on a major surface of a substrate body, said layer structure comprising
a) spaced apart first and second reflectors defining a microcavity of effective optical length L; -
b) at least one active layer that comprises organic material capable of electroluminescence, and having an electroluminescence spectrum including an emission region, with at least a portion of the active layer disposed between said reflector means; and c) electrodes that facilitate flowing a current through the at least portion of the active layer such that the microcavity can be caused to emit radiation; CHARACTERIZED IN THAT d) the layer structure comprises at least a first and a second active layer, with at least a portion of each of said active layers disposed between said reflector means, and with said first and second active layers having a combined electroluminescence spectrum including an emission region; and e) the effective optical length L is selected such that the microcavity is a multimode cavity that simultaneously supports at least two modes of radiation, each of said modes having a wavelength within said emission region of said combined electroluminescence spectrum, such that the microcavity can simultaneously emit radiation of at least two predetermined colors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification