Background Information

What is organic electronics?

Organic electronics is a branch of electronics that uses organic semiconductors in place of traditional inorganic semiconductors in electronic devices. Three types of organic electronic devices have received much attention in recent years. They are organic light-emitting diodes (OLEDs), organic thin-film transistors (OTFTs), and organic solar cells (OSCs) or organic photovoltaics (OPVs).

Fig. 1. Schematic structures of OLEDs, OTFTs, and OSCs and the chemical structures of some organic semiconductors. (Blue dots = nitrogen atoms, red dots = oxygen atoms, and dark-gray dots = metal atoms. Single bonds and double bonds are not differentiated here.)

The current status of organic electronics

OLEDs

OLED technology has made considerable progress towards commercialization in recent years. In 2007, Sony launched world's first 11-inch 3-mm thin OLED TV (XEL–1) to market, which is truly a milestone for the organic electronics. Although prototypes, some with larger screens, were demonstrated either before or after the introduction of XEL–1, it is the only OLED TV you can now buy home at a price of $2,499.99 (June 2009). It is expected more OLED TVs with larger screen and cheaper price will enter the market in the next one or two years.

Fig. 2. Sony XEL–1 HDTV with 11-inch OLED screen.

On the other hand, small OLED displays are doing pretty well in portable consumer electronic devices such as cell phones and music players. These small OLED displaces are expected to become more commonplace in the coming years.

Fig. 3. Sony music player with OLED display.

Flexible OLED displays have been demonstrated many times by several companies in the last a few years. But they are still far from being commercialized. One major problem to be solved is the stability issue. Flexible substrates are not as good as glass substrates to block water and oxygen – the main substances causing device degradation.

Fig. 4. Flexible OLED display from Sony.

Several companies are working to bring OLED light panels into your room. Right now there are no commercial products available yet. But real products are expected to appear in a few years.

Fig. 5. OLED light from GE.

OTFTs and OSCs

OTFTs and OSCs have two major advantages over their inorganic counterparts based on amorphous Si technology. The first advantage is that they are compatible with flexible plastic substrates. The second is that they can be made by solution process, such as printing. Combining these two advantages means that they can be made by low-cost, large-scale, roll-to-roll process, just like how newspapers are made.

Most of research on OTFTs and OSCs is currently done in universities. Though there are several companies founded in recently years that are dedicated to bring OTFTs and OSCs into market. Some prototypes such as OTFT-driven flexible display and flexible OSC panels have been demonstrated. But the competition from newly-developed flexible amorphous-Si technology might be intense in the coming years until the roll-to-roll process matured for organic devices.

Fig. 6. Readius by Polymer Vision – flexible E-ink display driven by OTFTs.

Fig. 7. Flexible OSCs from Konarka.

The future of organic electronics

I love science fiction films. One of the reasons is that they can offer a glimpse of the future, which is especially true for Steven Spielberg's Minority Report. During the film making, the production design team consulted many scientists for what the future might look like. The combined efforts from the artists and scientists made the future in Minority Report so breathtaking and in the mean time scientifically founded. I am amazed how they visualized the future of organic electronics in the film, let's take a look at two examples.

Transparent OLED displays. These might be not so far away, actually. Some prototypes have been demonstrated. Question is: whether you like these transparent displays to replace the traditional ones. But the transparent displays do look very cool.

Cheap, disposable electronics everywhere, even on the package boxes and newspapers. Presumably, the displays on the package box and newspaper below are driven by OTFTs, and possibly powered by OSCs printed on the paper. Unfortunately, we might need to wait several decades before these cool things show up.

Fig. 8. Transparent display and package box that can display animation. Please pay attention to the moving characters on the package box Tom Cruise picked up.

Fig. 9. Newspaper that can update its contents.