Laser-printed interdigitated Ag electrodes for organic thin film transistors

Pentacene-based thin film transistors (TFTs) with top contact (TC) and bottom contact (BC) configurations were fabricated on glass substrates using laser-printed silver nanoinks as the bottom gate and source/drain electrodes with a cross-linked poly-4-vinylphenol dielectric layer. Nanostructured source/drain Ag electrodes with various channel lengths (10–100 µm) were successfully fabricated on the pentacene layer without any damage from the Ag nanoink solvents due to the use of a semi-dry laser transfer process. Compared with the BC transistors, the TC transistors exhibited improved ohmic contact behaviour between the drain/source electrodes and the pentacene layer, which resulted in efficient charge carrier injection with higher drain current values than those obtained from the BC transistors. Analysis of the contact characteristics also showed a reduced contact resistance for the TC transistors than those from the BC transistors. The TC-TFTs exhibited a field-effect mobility of 0.11 cm2 V−1 s−1, an on/off current ratio of ∼105and a threshold voltage of −2 V in the saturation region.