UV-inkjet OLEDs - A new technology

Polymertronics was set up in 2006 to develop technology to produce inkjet-printable, ultra-violet (UV) curable organic light-emitting diode (OLED) fluids. OLEDs that can be printed on standard UV-inkjet equipment have many advantages. They are much quicker and cheaper to produce than standard OLEDs, they can be designed and manufactured with very short lead times, they can be printed on to a range of exotic surfaces including flexible ones, they give a much sharper image than conventional OLEDs, and they have a huge range of uses in medicine, advertising, logistics, the security industry, smart packaging and other areas. UV-curable OLEDs can also be printed with UV-curable coloured inks.

 

An OLED polymer which can be cured with UV light in a few seconds has already been developed by the company. A 16 mm2 area will now light consistently and brightly and the longevity of the OLED has been improved from a few minutes to over 30 hours. At the same time a UV-curing system which can be attached to an industrial printer has been developed and a prototype is working satisfactorily. The drive electronics are being improved and reduced in size, so that a 5-volt power source is sufficient to light an OLED for 30 hours.

 

OLEDs can be used for simple display screens, including hexadecimal displays, and are ideal for marking time-sensitive items, such as drugs or food packages. In time, it will be possible to develop printed OLEDs sufficiently to light up advertising posters with flashing lights and moving messages - improvements to conventional advertising hoardings which are currently hugely cumbersome and costly to implement.

 

 

The research and development has so far delivered:

 

1. Several light-emitting OLED systems

2. Successful UV curing of OLED systems

3. Techniques to improve manufacturing reliability

4. Four patent applications

5. Establishment of key parameters affecting OLED irradiance

6. Establishment of key parameters affecting OLED longevity

7. OLED drive electronics

OLEDs were first invented by Eastman Kodak in the early 1980s and development since then has been impressive. OLEDs are used routinely in many display screens, such as those for mobile phones and for low-level lighting of dashboards. Recently, substantial investment has been made in research for developing OLEDs to replace incandescent and fluorescent light bulbs as a primary lighting source.

 

Polymertronics' OLEDs are produced by blending chemicals containing a light-emissive component with a UVcurable polymer. When printed, this mixture is then exposed to a UV light source and cured to a flexible solid within four seconds. The purpose they serve is for bespoke product displays such as 7-segment displays and the like.

 

 

The benefits of organic technology are numerous. For both non-UV curable OLEDs and UV curable OLEDs, there are common benefits:

 

1. Printing on flexible and rigid media such as plastics, vinyl, glass and metal

2. Immediate product demand - zero lead time

3. Flexible media

4. Fast response to applied voltage for rapid changing graphics

5. Wide viewing angle of OLED devices

6. Very high definition for display

 

Beyond the common advantages, UV-inkjet OLEDs have further advantages:

 

1. Simple, fast manufacture

2. Low product waste results in a 'green' technology

3. Instant curing following printing

4. Print-on-demand technology

5. Zero product-volume loss during process

of how UV-curable OLEDs and touch sensors can serve respective markets. The company has a range of products and services to assist enterprises in various technology sectors:

 

Smart packaging is packaging which goes beyond that of conventional design and functionality to include mechanical, chemical, electrical and electronic features. In the case of OLEDs, for high value goods this could take the form of a small matrix display with a flashing logo, or a scrolling advertising message.

 

OLEDs will add new and unparalleled layers of safety to consumer products. For example, it will reassure consumers that products and brands are genuine, that they have not been tampered with, and that they are within their use-by date.

 

 

In conjunction with radio-frequency identification (RFID), OLEDs can also be used for product identification. RFID in retail has made rapid progress over recent years. Over 500 million labels were used globally on pallets and cases in 2006, including those containing food, beauty and pharmaceutical products. By 2015, there could be over 400 billion RFID labels fitted to consumer goods.

 

According to the UK's National Health Service, unclear packaging and labelling contributes to 25% of medication errors. The University of London has studied people reading packaging and found that 25% of fullsighted people have difficulty reading packets and other instructions.

 

Difficulty with reading information on packaging arises for a number of reasons. The label design or legal requirements may necessitate a smaller font to fit all of the information on the label. Integrating OLEDs into the packaging could highlight the most important details of a drug through an interactive display.

 

In the interests of sterility, many medical devices are used only once. For this to be viable, such devices must be cheap to produce. Inkjet printing enables a component of a medical device to be manufactured quickly and with significantly less tooling than is presently required. Further, medical devices are often sealed until they are used. With Polymertronics' technology, this has the beneficial effect of helping to preserve a device's OLEDs.

 

 

Advertisements can already be backlit, but with printed OLEDs the illumination can be incorporated into the advertisement itself relatively cheaply. There is no tooling required and print designs can be executed quickly. For a fast-paced industry such as advertising, this reduction in lead-time offers a substantial advantage.

 

Printed OLEDs could be extremely valuable in aiding anti-counterfeiting measures and in tracking goods in transit. Embedded customised data presents fraudsters with a new hurdle. Furthermore, tampering can be quickly and easily detected and data can be changed often to keep ahead of criminals.

 

Samsung SDI and the German company Bundesdruckerei are developing a new passport with a tiny polycarbonate data page, which contains an active matrix bendable OLED display, capable of showing video or text regarding the passport holder. The display itself does not use a battery; it is activated by a reader, which transmits electricity by induction. For visa applications, printed OLEDs could incorporate colour graphics with a display providing individual detail for little expense.

Polymertronics is presently working on improving its OLED chemistry for inkjet printing. There are also commercial collaborations in motion with smart packaging and other display companies. Objective for the next two years are to build upon the present achievements and take the company's products to commericalisation:

 

 

1. Advance UV-curable OLED chemistries (patents)

2. Reduce OLED drivers from PCB to simple chipsets

3. Commercial OLED products

4. Collaborate with businesses that can deliver parts to inkjet print a complete OLED system

 

The company is presently engaged in due diligence for second round funding. The company is inviting subscriptions to bring the technology to full commercialisation in 2010.