Progress with Printed Electronics

Printed Electronics is an old embryonic technology. It is an umbrella term used to describe electronics that can be flexible, printed and/or based on organic materials. It consists of a wide range of enabling technologies, each at different points of maturity, growth and development. Among others, printed electronics technologies are used for components in consumer goods and healthcare applications like displays, power and other components such as logic, sensors, and conductive inks.

Display Applications

AC Electroluminescence Displays

AC Electroluminescent Displays are simple, screen printed light emitting displays that require an AC power source. They are built of low cost, light emitting segments that can be relatively thin and conformable.

Examples of cases studies include moving images on labels for rum and whisky promotional bottles, as well as boxes and other promotional off-package signage (posters etc.). EL displays are also widely used on wearables such as promotional/novelty T-shirts.

Electrochromic Displays

Electrochromic (EC) displays are very simple, screen printed structures, characterized by low power consumption. They are low cost reflective displays that have been used in promotional material such as gift cards and magazine covers. Beyond those, it's mostly been prototypes so far, such as displays for smart cards, gift cards etc. Holding it back is the limited choice of colors but chemical companies are working on a broader color range which will enable more applications.

Electrophoretic Displays

Electrophoretic displays (EPDs) have been extensively used in e-readers such as the Amazon Kindle, but this is a market that is currently in decline as consumers opt for color LCD versions. Consumer goods and healthcare applications have seen e-paper displays as one-offs in magazines, POS posters, in products such as key fobs, memory sticks, locks etc. These have been fairly niche applications so far, but technology developers are looking to push further adoption in these markets due to the slow-down in the e-reader space. In addition, there is work on color versions, with striking red recently demonstrated along with grayscale.

OLED Displays

OLED Displays are light emitting. They can be flexible and printed but are currently mostly made by vacuum processes. Printing is possible and extensively researched but not in commercial products yet. The materials are light emitting materials characterized by low power consumption and excellent color range but are still very expensive.

Best known is their use in smart phones and televisions: OLEDs are already a $15.7 billion market in 2014 for cell phone displays, OLED TVs were launched in 2013. In the CPG space there have been very limited demonstrations. Drawbacks for further adoption beyond consumer electronics include:

• Costs are still high, approx. $30 for a cell phone display including backplane.
• Lifetime for flexible versions is very poor unless a large amount of money is spent on good flexible barriers (which cost more than glass)
• Focus is to make high volume, high margin products like consumer electronics for now to recoup high R&D spend rather than low margin products.

Power Applications

Printed Batteries

Thin film batteries - usually MnOZn chemistry when printed (but rigid, lithium ion solid state versions are also available) are very important components since all devices need a power source which needs to be safe and as "green" as possible. Skin patches and audio paper/recording gift cards have been successful applications. In particular, in a skin patch the battery puts a voltage potential over the skin so that the pores open up and cosmetic goes in about 10 times more quickly - used for fast anti-wrinkle treatments.

Costs are a few tens of cents each in low volume. Lifetime and power output are not as good as a coin cell - if a coin cell can be used, it probably will be preferred over the form factor benefits of a thin film cell until volume sales are achieved. Driving applications are the need for thin, flexible batteries such as in wearable electronics.

Photovoltaics, OPV & DSSC

In the photovoltaics space, Organic PV and dye sensitized solar cells (DSSCs) can perform optimally in indoor applications (i.e. lower levels of light intensity) where other PV technologies can struggle. Companies are pursuing these to power electronic shelf edge labels to signage, as they work well at low light levels and the solar cell can be designed around the bezel and even colored to look better than conventional PV cells. Reducing costs and optimizing lifetime and efficiency remain the biggest challenges for these technologies so far.

Wireless Power Transfer

Wireless Power e.g. via NFC would remove the power source cost component which would enable smart packaging features at lower costs. Demonstrations such as interactive packaging that is powered wirelessly via induction have already been showcased.

Other Components

Logic

Printed or organic low cost, low transistor count devices would satisfy the needs for logic required for many mainstream applications. There has been efforts to print RFID tags but although these have been demonstrated, they are not commercial yet. The industry is working on many product prototypes and smart packaging concepts such as winking gift cards, interactive bottle labels with LED lights, or printed time temperature indicator labels, incorporating printed memory, logic, temperature sensors, battery and display.

Conductive Inks

The application here is printed ink for simple conductors, resistors, capacitors and heating elements. Innovations include printed conductors on a card that can be "read" by a multi touch screen and launch a program or smart shelves to monitor stock units. Costs are variable depending on the device made, and many devices today are hybrid devices, with several very different technologies integrated, where ink is not the dominant cost.

Sensors

The biggest success has been glucose test strips, a multi-billion dollar market that uses printed conductor electrodes on each strip. Beyond that there are many other types of sensors coming to market. Demonstrators/prototypes are available such as motion sensors that detect someone's presence, or temperature sensing.

Many of the products mentioned here will be showcased at the forthcoming Printed Electronics USA 2014 trade show and conference on November 19-20 in Santa Clara, California, USA.