Enhanced field-effect mobility in pentacene based organic thin-film transistors on polyacrylates

Abstract

We reported on organic thin-film transistors (OTFTs) with high dielectric constant polymer, poly(2,2,2-trifluoroethyl methacrylate) (PTFMA), as the gate dielectric. In top-contact OTFTs, the field-effect mobility was enhanced by applying a dielectric buffer layer poly(α-methylstyrene) to the bare PTFMA. After improving interfacial affinity within the active layer/dielectrics, deposited pentacene grain size and device performance were enhanced dramatically. The corresponding mobility, threshold voltage, and on/off current ratio were 0.70 cm2 V−1 s−1, −10.5 V, and 5.4×105, respectively. The moderately improved interface also suppressed the hole-trapping effect, which led to less hysteresis and minimized threshold voltage shift.

Solution-Processed Rare-Earth Oxide Thin Films for Alternative Gate Dielectric Application

“…The values of surface energy are 24.07, 40.77, and 46.70 mJ/m 2 for Er 2 O 3 modified by ODPA, HMDS, and PS, which agrees well with the trend of increasing mobility of corresponding transistors, indicating lower surface energy yields larger semiconductor mobility, consistent with reported results both in pentacene and polymer semiconductor based transistors. 44,54,58,59 Furthermore, bias stress effects have been investigated to characterize the influence of surface modification on device stability. As shown in Figure S12, transistors based on ODPA-, HMDS-, and PS-modified Er 2 O 3 dielectrics maintain 58.6, 52.5, and 90.4% of their initial drain currents after a bias of V GS = V DS = −3 V for 10 4 s. Superior stability is found in the transistor with PS-modified Er 2 O 3 dielectric compared with that of the other two, suggesting that best passivation on the defects of pristine Er 2 O 3 is formed owing to its densified polymeric structure.…”