Channel length dependent characterisations of organic thin film transistors with solution processable gadolinium phthalocyanine derivatives

Spin-coated 52-nm-thick films of newly synthesised gadolinium liquid crystalline bisphthalocyanine sandwich (GdPc 2) complexes with octyl chains non-peripheral positions have been successfully employed as active layers for bottom-gate organic field effect transistors having both short (5μm) and long (20μm) channels. The scaling down of the channel length (L) decreases the field effect mobility due to the increase in the contact resistance between the gold electrodes and the GdPc 2 semiconducting layer. Values of on–off ratio and sub-threshold voltage swing are higher nearly one order of magnitude for L=5μm than those for L=20μm