Enhanced Performance of Au/P3HT/(Bilayer Dielectrics)/Si Thin-Film-Transistor Having Gold Nanoparticles Chemically Bonded to P3HT

The charge transport enhancement of using poly(3-hexylthiophene) covalently bonded with gold nanoparticles as an active layer in a bottom-gate/top contact, Au/(P3HT)/(bilayer dielectric)/Si OTFT device has been studied. P3HT was synthesized via the modified Grignard metathesis method and functionalized to have a thiol terminal (P3HT_SH). Gold nanoparticles (AuNPs) with sizes ranging from 2 to 10 nm were then formed via a reduction of HAuCl₄ in the presence of P3HT_SH. Compared to the pristine P3HT, the AuNPs-containing P3HT composite materials have a higher energy level of HOMO and a smaller electrochemical bandgap E _g ^chem. The smaller bandgap enhances the charge carrier mobility and the higher HOMO energy level indicates a reduced barrier and an increased injection rate for charge carrier at the source contact. Furthermore, the threshold voltage V _T of AuNPs-containing P3HT samples remain nearly unchanged and their saturation current I _D and the field–effect mobility are higher. An OTFT device fabricated with a composite sample containing 1.30% AuNPs has a carrier mobility and saturation current nearly two time higher than pristine P3HT.