Electroplating Engineers of Japan and the University of Tokyo claim to developed an electroless plating process which enables the simultaneous formation of contact electrodes for p-type and n-type organic field effect transistors (OFET).
The process, which uses silver nanoparticles as a catalyst, allows the formation of top contact OFET contact electrodes without the need for a vacuum. According to the partners, more advanced organic electronic devices can now be formed at a lower cost.
For p-type organic semiconductors, the contact resistance is said to be 0.1kO-cm or less – the lowest value yet achieved without a vacuum.
This technology enables the creation of contact electrodes with a gold-silver hybrid structure. It starts with the application of a silver catalyst solution, after which a gold coating is applied to the substrate by immersing it in an electroless gold plating solution, filling the gaps between the silver grains with gold.
The collaborators acknowledge there are other methods for the formation of OFET contact electrodes, but claims these suffer from such issues as requiring a vacuum environment or can damage the organic semiconductors.
They say thin film electrodes can be formed uniformly using vacuum deposition, but this approach is expensive and the loss of materials is 'huge'. Also, while electrode formation in the atmosphere is possible using metallic ink and metallic paste, this requires the inclusion of organic solvents, high temperature sintering and hardening by means of ultra violet radiation, which can also damage the organic semiconductor.
Author
Graham Pitcher
Source: www.newelectronics.co.uk