Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Reexamination Certificate
1998-11-16
2001-08-14
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
C313S503000, C313S504000
Reexamination Certificate
active
06274980
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of light emitting devices, in particular, to stacked organic light emitting devices (SOLEDs).
BACKGROUND INFORMATION
Organic light emitting devices (OLEDs) are light emitting devices that use organic electroluminescent (EL) materials excited by electric current to emit light. A plurality of OLEDs can be arranged in an array, for example, to form a display.
OLEDs enjoy several advantages over light emitting devices formed with other technologies. Some of the advantages of OLEDs include high efficiency, the ability to emit light from a relatively large area, the use of low cost materials, the ability to use a wide variety of substrates, a wide viewing angle, low voltage operation, direct emission and high reliability.
The intensity of light emitted by an individual OLED, while favorable in comparison to other devices, may be inadequate for certain applications in which higher intensity emission is required or desirable. In such cases, light emitting devices of other technologies are required, thereby losing the aforementioned advantages of OLEDs.
SUMMARY OF THE INVENTION
The present invention is directed to a high brightness organic light emitting device (OLED). The device of the present invention comprises a vertical stack of OLEDs, i.e., a “stacked” OLED (SOLED), in which the OLEDs in the stack simultaneously emit light of the same color.
In an exemplary embodiment of the present invention, a SOLED is formed by stacking two or more “transparent” OLEDs (TOLEDs). A highly reflective electrode is used at one end of the stack. The other end of the stack is substantially transparent, thereby allowing light to be emitted therethrough. The intensity of the light emitted is substantially the sum of the intensities of the emissions of the individual OLEDs. Each OLED in the stack emits substantially the same amount of light it would emit in a stand-alone configuration. However, because at least some of the light emitted from an individual OLED in the stack must travel through one or more other OLEDs in the stack, some light will be absorbed within the device.
The high brightness OLED of the present invention can be used in a wide variety of applications, including computer displays, informational displays in vehicles, television monitors, telephones, printers, illuminated signs, large-area screens and billboards.
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U.S. Patent Application Serial No. 08/858,994, filed May 20, 1997, entitled “Saturated Full Color Stacked Organic Light Emitting Devices”.
Burrows Paul E.
Forrest Stephen R.
Gerike Matthew J.
Kenyon & Kenyon
Patel Nimeshkumar D.
The Trustees of Princeton University
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