With the development of organic electronics it has become clear that the choice of substrate is essential to make the technology viable. Requirements are for flexible substrates, thin, light, robust and conformable. The combination of flexible substrates with deposition of polymers by printing technics opens up the possibility of inexpensive fabrication of large area systems by roll-to-roll processing.
Bacterial cellulose (BC) is a pure form of cellulose and is naturally produced by the bacteria Glucanacetobacter xylinus[1]. BC and BC-based materials have great potential to be used as substrate for electronics since they possess adequate electronic properties, resistance to high temperatures, and high flexibility. BC has also the advantages of being renewable, biodegradable and biocompatible.
The properties of BC compare well with the commonly used substrate materials for organic electronics application, such as, poly(ethylene naphtalate) (PEN) and poly(ethylene terephtalate) (PET). BC has a low coefficient of thermal expansion (0.1-6 ppm/°C) as for PEN is 18-20 ppm/°C and for PET 20-25 ppm/°C. BC it is stable upon 260 °C[2] (PEN and PET are stable upon 220°C and 150°C, respectively) and its dielectric constant is in the range of k = 1.6 − 1.9[3].
The presented work aims at the design and development of organic thin film transistors (OTFTs) fabricated by inkjet printing using BC as substrate. OTFTs fabricated over glass are used as standard for comparison of performance. Silver contacts and polyvinylphenol (PVP) dielectric layer are fabricated by inkjet printing using a Dimatix Materials Printer 2831. Pentacene, deposited by thermal evaporation, was used as semiconductor. The BC was flattened by using a layer of PVP.