Organic Chemists Contributing to the Development of Plastic Electronics
Background - Why is this important?
Electronic media are becoming increasingly important for consumers and advertisers. One of the most exciting developments in the display industry has been the emergence of Polymer Organic Light Emitting Diodes (P-OLEDs).
Organic Light Emitting Diode
Current Organic Light-Emitting Diode (OLED) technology already competes with, and in some areas exceeds, the performance of liquid crystal and plasma displays, but additional advances in this area of P-OLEDs, which are also referred to as plastic electronics, will allow further development.
Plastic electronics is a branch of electronics dealing with semi-conductive polymers and semi-conductive small molecules. The technology is based on the use of an organic polymer that emits light when sandwiched between electrodes and charge is injected subjected to electronic charge. They offer significant advantages over liquid crystal displays (LCDs), in which a separate light source has to be filtered to produce an image. Already, OLED technology has been used in various products such as mobile phones, electric shavers, MP3 players and medical devices. P-OLEDs will also soon be used in a range of applications including televisions, lighting and flexible displays allowing brighter, clearer displays and the potential for cheaper and longer lasting display features.
What did the organic chemists do?
Use of PPV in development of P-OLED
In 1989 a team of chemists and physicists at Cambridge University discovered that poly(p-phenylene vinylene) (PPV) emits a yellow-green light when it is sandwiched between a pair of electrodes.1 Although the efficiency of this first P-OLED was very low, the potential of displays that emit their own light was rapidly recognised. Over the past twenty years, a multidisciplinary effort involving synthetic chemists, physicists and device engineers working in academia and industry, have led to on a wide range of advances in P-OLED science and technology.
Synthetic organic chemists developed a range of reactions to change parts of the PPV and related polymers to alter the wavelength of light that the polymer emits, improve its luminescence efficiency, increase its stability, and making them easier to process from solvents by changing their solubility.2,3
This fact that light emitting polymers can be made soluble in organic solvents is a major advantage of the technology and means that this technology can be readily employed to deposit the thin film (e.g. by ink-jet printing) on a display substrate without the need for vacuum deposition methods. If all the electrical energy can be harnessed as light P-OLED technology could be more energy efficient and (as mentioned) has the advantage that it can be printed over large areas.
What is the impact?
Plastic electronics are used in P-OLEDs, are predicted to lead to the creation of a whole new range of products such as conformable and rollable electronic displays, ultra-efficient lighting and low-cost long-life solar cells.
UK physicists and chemists are playing a major role in developing newer plastic electronics. Several university spin-out and start-up companies are working to commercialise P-OLED advanced technologies including: Cambridge Display Technology (CDT), MicroEmmisive Displays, Lumicure, Molecular Vision and Plastic Logic (transistors based on polymers). The market value of plastic electronics is forecast to rise from $2 billion in 2009 to $120 billion by 2020.
1 J H Burroughes, D D C Bradley, A R Brown, R N Marks, K Mackay, R H Friend, P L Burn, A B Holmes, Nature, 1990, 347, 539
2 A C Grimsdale, K L Chan, R E Martin, P G Jokisz, A B Holmes, Chem. Rev., 2009, 109, 897
3 U Mitschke, P Bäuerle, J. Mater. Chem., 2000, 10, 1471
Also of interest
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Cambridge Display Technology (CDT)
Cambridge Display Technology (CDT) is the leading developer of technologies based on polymer light emitting diodes (P-OLEDs)
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Contact and Further Information
Dr Anne Horan
Programme Manager, Life Sciences
Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge, CB4 0WF
Tel: 01223 432699