Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Patent
1998-02-17
1999-07-27
Patel, Ashok
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
313509, 313512, 313 1, 428917, 445 24, H05B 3314
Patent
active
059295627
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to composite organic light-emitting devices and their fabrication.
BACKGROUND TO THE INVENTION
Polymer organic electroluminescent devices such as described in U.S. Pat. No. 5,247,190 and molecular organic electroluminescent devices as described by C. W. Tang, S. A. Van Slyke and C. H. Chen in J Appl. Phys. 65, 3610 (1989) have been demonstrated with emission bands in all parts of the visible spectrum. Therefore this technology is amenable for use in multi-colour or true RGB emissive displays and these can be simple uniform lights, alphanumeric and dot-matrix displays or high-resolution displays. In order to achieve the desired multi-colour effect, pixels with different emission bands have to be processed/manufactured on a substrate next to each other. This requires patterning steps which can be very difficult to implement, even on a laboratory scale; the organic layers may not be compatible with the patterning processes and/or cross-talk between adjacent devices of different colours may occur. The devices emitting different colours can also be processed on top of each other with the higher energy light emission organic layers in front followed by the layers responsible for the lower energy light emission. Again, patterning and cross-talk issues are very important here and can add significantly to the device and manufacturing complexity. The same issues are relevant in devices in which various degrees of patterning complexities are required, such as in a combination of a uniform emissive area with a higher information content display.
If such organic light-emitting devices with multi-colour emission and/or different patterning complexity are fabricated on one substrate where the active emissive organic layers, electrodes, and additional layers are sequentially deposited, then all processing steps (deposition of the organic electroluminescent layers, transport layers, electrodes, patterning, etc.) for all pixels and patterns of all employed colours and shapes have to be free of crucial defects and the yield for each processing step has to be high in order to result in an acceptable and economically viable total production yield and cost for the final display. Also, each change in one or more of the features of the final display, for example changing one of the emission colours or patterns in a display, may require a costly and significant if not complete re-design of the manufacturing process. The processes of making electrical contacts, testing, yield control, etc. can be very critical and complicated in a more complex display. Furthermore, individual processing steps, for example a heat treatment for one of the organic layers, may only be poorly or even not at all compatible with materials and/or structures already on the substrate or the substrate itself.
The invention describes organic light-emitting devices which have one or more emission colours and/or one or more emission patterns and/or emission directions and describes a general and versatile method for the fabrication of such devices which avoids the problems described above and has further significant advantages which manufacturing methods have hitherto been unable to exploit.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a method of fabricating an organic electroluminescent display, which comprises laminating together a plurality of self-supporting organic light-emitting devices, each of which is capable of functioning separately as an individual device; wherein each of the organic light-emitting devices in the display emits radiation differently from one another in respect of colour, pattern and/or direction; and wherein each of the organic light-emitting devices in the display comprises a substrate, a first electrode and a second electrode, at least one of which electrodes is at least semi-transparent, and an organic electroluminescent layer between the electrodes.
The organic electroluminescent layer may comprise a conjugated polymer capable o
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Cambridge Display Technology Limited
Patel Ashok
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