Organic Light Emitting Diodes (OLEDs) are bright and energy efficient devices used now mainly for displays. They can also be exploited for lighting, providing diffuse and large scale luminaires to complement inorganic LED lighting technology. However, the best performing OLED devices are normally based on iridium and platinum emitters, which are rare and expensive materials.
We have demonstrated that palladium, which is both cheaper and more abundant, can act as a promising alternative emissive material. Our materials, based on luminescent ditopic Pd(0) complexes, are the most emissive palladium complexes reported to date and have easily tuneable emission energies making them an ideal new family of candidates for OLEDs. Indeed, the first OLEDs have been fabricated based on such materials.
Palladium is more abundant and cheaper than iridium, making this a more viable source of emitters for OLEDs and related technologies. The complexes are extremely bright, since they have a full d10 electronic configuration which circumvents any possibility of populating “metal-centred” (MC) excited states that are known to deactivate them. Only the desirable metal-to-ligand charge transfer states (MLCT) are possible. In addition, the ligand scaffold can easily be modified in terms of its electronics, which affects emission colour, and steric bulk, which has a strong influence over the brightness of these materials.
- A family of highly luminescent palladium complexes
- Wide range of accessible colours
- Structures easily modified to improve brightness or further tune emission colours
- Based on palladium which is more abundant and cheaper than iridium and platinum which are more commonly used for lighting displays
- Organic light emitting diodes (OLEDs)
- Due to the unsaturated nature of the palladium complexes these materials could be used for small molecule detection e.g. H2, O2 or small VOCs.
Subject to a UK patent application GB1421390.4 filed 2 December 2014.
Further information may be provided under an appropriate NDA.