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Energy-Saving Research Shines Light on OLEDs

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As the debate over global warming continues, the quest for sustainable energy solutions is at the forefront of scientific research around the world.

With the depletion of fossil fuels and the safety of nuclear power under scrutiny, the search is on for clean renewable sources and efficient processes to sustain the planet’s increasing electricity demands.

Studies into resource-hungry lighting, which constitutes around 19 per cent of the total power consumed on earth, are seeing real breakthroughs in energy-saving research. At the University of Hong Kong, a team from the Chemistry Department is investigating the luminescent properties of metal complexes and the range of colours they produce.

The work is being led by Professor Vivian Yam, Philip Wong Wilson Wong Professor in Chemistry and Energy and Chair Professor in Chemistry at HKU. Professor Yam’s research covers synthetic inorganic/organometallic chemistry, with a particular focus on the molecular design and synthesis of new classes of light-emitting materials.  The colours, brightness and efficiency of these materials are tested in the solid state, in thin films and in solutions of different compositions.

Of particular interest to Professor Yam is the use of efficient phosphorescent materials in OLEDs, or Organic Light-Emitting Diodes, which are devices that show luminescence when a voltage is applied.

While research in OLEDs is not new, Professor Yam and her team are trying to discover new classes of efficient OLED materials that are unique and that will generate Hong Kong-owned IP rights. In particular, an understanding of the interactions between molecules and the control of these interactions will help to produce more efficient materials.

"I want to try to understand the nature of light emission and how one can really use chemical methods to tune the emission colours as well as energies," she said. "I think we are filling the gap here because most people have been just modifying the molecules but here the uniqueness is to find luminescent metal complexes that emit phosphoresence."

The result of these experiments is that Professor Yam is finding more efficient processes for lighting with the long-term hope that the same brightness can be achieved with lower power input and ultimately increased energy saving.

The luminescent materials also have the potential for use as sensors in biological and environmental applications, while the team’s work on light-absorbing materials could in future be used for solar energy conversion such as in organic solar cells.