The term 'nanotechnology' is widely used today, and P-OLED technology can certainly be thought of as an example. The total thickness of all layers in a P-OLED display device can be less than 500nm, so that in effect, the thickness of a display is similar to the thickness of the substrates (usually glass) that form the top and bottom of the device.

The structure of a basic P-OLED display device can be extremely simple, consisting of a sandwich containing:

• A transparent conducting electrode with a large work function (Anode). Indium tin oxide (ITO) is commonly used, coated on a substrate
• A conducting polymer layer which transports and injects holes into the active layers (Hole Injection / Transport Layer)
• A thin organic interlayer material sometimes referred to "primer layer" developed by CDT to improve efficiency and lifetime
• A thin light emitting polymer (LEP) layer less than 100nm thick (Emissive Layer)
• A metallic electrode with a low work function, such as a barium/aluminium bi-layer (Cathode)
  

Compared to competing technologies such as LCDs, the structure of a P-OLED device is extremely simple. The ability to  dissolve the active materials (Hole Injection/Transport Layer, Interlayer/Primer Layer and Light Emitting Polymer) in a solvent to form an "ink" and deposit by a range of printing techniques on a wide variety of substrates at low temperatures provides a number of manufacturing advantages over small molecule OLED technology. The simplicity and solution processability of P-OLED materials together make P-OLEDs an exciting prospect for future display applications from small mobile displays though to large screen TVs and large area panels for lighting.

In operation, voltage is applied across the contacts, creating an electric field and injecting charges into the polymer where they recombine and emit light.  P-OLEDs offer the ultra-fast switching speeds typical of LEDs (and around a thousand times faster than LCDs!).

Since the first devices were fabricated, very rapid progress has been made in improving the quantum efficiencies of P-OLED devices. Initially, internal quantum efficiencies of only 0.01% were achieved (defined as the number of photons generated in the polymer film relative to the number of carriers injected into the polymer). Today, figures three orders of magnitude higher are possible.

These improvements have been developed through a combination of new materials development, device engineering and process optimisation, and CDT has extensive activities in all these areas. The Interlayer/Primer Layer technology introduced by CDT enabled substantial improvements in both efficiency and stability to be achieved. The thin solution processed layer, inserted between the LEP and Hole Injection/Transport Layer assists with balancing hole and injection & transport, improving the efficiency of radiative recombination that leads to light emission and controlling where the light is emitted in the device.