Correlation between the interface states and ultraviolet treatment for low-voltage pentacene thin-film transistors

We report a comparative study on the interface states of pentacene thin-film transistors (TFTs) with ultraviolet (UV) illumination. The trap density (negative fixed charge) at the pentacene/poly-4-vynylphenol (PVP) interface of the TFT adopting UV-treated poly-4-vynylphenol (PVP) layers (prior to pentacene deposition) can be estimated at 1.75 × 1012/cm2 while another UV-treated TFT (after pentacene deposition) displays higher trap density of 2.40 × 1012/cm2 due to the additional negative charges at the interface generated from pentacene channel layers through UV treatment. It can lead to the formation of more conductive channels and thus effectively modulate the threshold voltage (VT). In addition, we fabricated the resistance-load inverter showing improved performance through UV treatment using load-line analysis.