Abstract
In this paper, we report the fabrication of a series of top-gate bottom-contact hybrid organic thin film transistors based on solution-processed semiconductors and dielectric layers on a glass substrate. Semiconductor active layers were based on a mixture of [6,6]-phenyl C61-butyric acid methyl ester (PCBM) mixture and poly (3-hexylthiophene) (P3HT), whereas gate dielectric layers were based on PMMA mixed with various concentrations of high-k Ta2O5 inorganic particles. Experimental investigation indicated that the hysteresis phenomenon of the devices can be governed by changing of the Ta2O5 concentration in PMMA-Ta2O5 nanocomposites gate dielectric layer. In addition, significant enhancement of electron transport was also observed with the increase of Ta2O5 inorganic particles concentration in the gate layer, which arises from the change of the charge transport from unipolar to ambipolar type. The fabricated OTFTs, with significant hysteresis variation as a function of Ta2O5 nanoparticles content in PMMA-Ta2O5 gate dielectrics, prove particularly promising in consideration of possible use for low-cost nonvolatile memory elements and sensing array applications.
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•A series of OTFTs based on solution-processed P3HT:PCBM blends were fabricated and characterized.•A solution based hybrid bilayer dielectric, containing PMMA and high-k Ta2O5 inorganic nanoparticles, is used as a gate dielectric layer of the OTFTs.•The effect of the sequence of PMMA/Ta2O5 nanocomposites on the hysteresis phenomena is studied.•As the concentration of Ta2O5 increases up to 7 wt% and higher, the hysteresis amount values (ΔVhyst) increase.•Active layers of OTFTs with 7 wt% and higher concentration of Ta2O5 showed n-type as well as p-type characteristics which leads to ambipolar behavior of the devices.