The effects of hydroxyl-free polystyrene buffer layer on electrical performance of pentacene-based thin-film transistors with high-k oxide gate dielectric

摘要

We have investigated the effects of hydroxyl-free polystyrene (PS) as buffer layer on pentacene-based low-voltage organic thin-film transistors (OTFTs). The PS buffer layer is formed on the HfO_2 layer evaporated on Si substrate by spin-coating method prior to pentacene deposition, existence of which results in a dramatic increase of field effect mobility from 0.09 to 0.59 cm~2/Vs and negligible hysteresis. The improved mobility and hysteresis of the OTFTs can be attributed to the formation of smooth and nonpolar hydroxyl-free PS/HfO_2 gate dielectric surface. The PS insulator buffer layer can also effectively reduce gate leakage current by more than 70 percent. The results demonstrate that using appropriate polymer buffer layer is favorable to improve the performance of the OTFTs operating at low voltages with high mobility and good electrical stability.