OLED firm Cambridge Display Technology (CDT) has eliminated expensive indium tin oxide (ITO) from organic lighting panels, replacing it with a fine copper mesh.
“This demonstration has shown the potential for patterned metal tracking using electroless metal deposition as a replacement for both ITO and traditional sputtered tracking,” said CDT. “ITO is widely used as a transparent conductor in the displays, lighting and photovoltaics industries, but is in short supply and expensive.”
ITO is also brittle and prone to cracking, particularly on flexible substrates
The copper mesh is not etched, but deposited using a process developed by Conductive Inkjet Technology (CIT), a subsidiary of optics firm Carclo.
CIT prints a pattern of catalyst on the substrate, which causes copper to be laid-down when it is immersed in a metal-containing solution.
Copper tracks under 10µm have been deposited on glass “resulting in a highly transparent, highly conductive surface without the voltage drops of ITO-based technologies,” claimed CDT. “By applying a conductive polymer to these grids, a true ITO replacement has been demonstrated.”
Jim Veninger is general manager at CDT.
“While further development is required, I can see CIT’s technology supporting processes for OLED lighting in the near future,” he said.
The results have come from a project called Nomad, which includes both CDT and CIT, and is part-funded by the Government’s Technology Strategy Board.
“We are extremely happy with the progress made in this project, and to see that this new approach may soon be ready for commercial exploitation in OLED lighting. This is yet another great example of world class businesses coming together in the UK to develop innovative technology with global market potential,” said the TSB’s lead electronics technologist Mike Biddle.