Editorial Feature

Organic Light Emitting Diodes, OLED’s - Principles, Advantages, Materials and Potential Applications

Organic Light Emitting Diodes or OLED’s are effectively light emitting diodes made from semiconducting organic polymers. They are currently still under development and have potential application in numerous fields. The technology has advanced such that applications are being envisaged and organisations are committing research funds to the eventual commercialisation of the technology.

Principle of Operation

Organic light emitting diodes are able to operate due to the phenomenon of electroluminescence. The OLED has an organic dye which consists of exciton states. These consist of an excited electron and a hole or empty state. When the hole and electron combine a photon is emitted and light is produced.

Advantages and Benefits of Organic Light Emitting Diodes

  • They have the potential to be able to be produced much more cheaply than conventional LED’s, LCD’s and plasma televisions using processes derived from ink-jet printing
  • Potential to produce much larger displays compared to LCD and plasma display technology, i.e. a more scalable production process
  • Improved range of colours and brightnesses compared to LCD and plasma displays
  • Potentially very energy efficient
  • They can be deposited on large substrates enabling large areas to be illuminated
  • Lighter than LED’s
  • Flexible
  • Can produce a true black and infinite contrast ratios

Materials Used in Organic Light Emitting Diodes

The polymer dye consists of derivatives of poly(p-phenylene vinylene) or PPV, while the anode and cathode are typically indium tin oxide (ITO) and aluminium respectively. Other materials may also be used in between these layers to increase the efficiency of the device.

Potential Applications

  • Domestic and commercial lighting with controllable colour
  • Televisions
  • Computer displays which will not require back lighting as in conventional LCD displays
  • Flat panel displays
  • Digital cameras
  • Mobile phones
  • Flexible displays

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