High Performance Amorphous Polymeric Thin-Film Transistors Based on Poly[(1,2-bis-(2′-thienyl)vinyl-5′,5′′-diyl)-alt-(9,9-dioctylfluorene-2,7-diyl] Semiconductors

Abstract

We have synthesized a new p-type polymer, poly[(1,2-bis-(2′-thienyl)vinyl-5′,5′′-diyl)-alt-(9,9-dioctyldecylfluorene-2,7-diyl] (PTVTF), via a Suzuki coupling reaction. PTVTF was found with UV–vis absorption spectroscopy, GIXD, AFM, and NEXAFS to be an ‘annealing-freeʼ amorphous polymer. Despite its amorphous nature, our time-of-flight measurements demonstrate that PTVTF is a good hole transport material with an intrinsic hole mobility of 2 × 10−4 cm2/Vs, which is comparable to those of crystalline polymers such as P3HT. A solution-processed PTVTF FET with a bottom gate/top contact geometry was found to exhibit good device performance with superior reproducibility. The field-effect mobility of holes was found to be 2 × 10−2 cm2/Vs with a good subthreshold swing of 1.7 Vdecade−1. The output characteristics indicate that good saturation and ohmic contact are present. The amorphous nature of PTVTF makes it a very promising candidate for commercial OTFTs since its properties are independent of fabrication conditions. From the temperature dependence of the mobility of amorphous PTVTF, we found that increases in the hydrophobicity of the dielectric substrate improve the mobility of PTVTF by reducing the trap density of the semiconductor layer.

Highly Emissive and Electrochemically Stable Thienylene Vinylene Oligomers and Copolymers: An Unusual Effect of Alkylsulfanyl Substituents

“…Accordingly, these treatments did not improve device performance. While mobilities approaching 10 −2 cm 2 V −1 s −1 are far from the champion values for organic semiconductors in crystalline form, they are quite close to the best mobilities observed in amorphous organic semiconductors 19, 42. We also note that the on/off ratio of 10 5 achieved by 7 is quite high as for solution‐processed device.…”

“…The thiophene analog of PPV, poly(thienylene vinylene) (PTV), however, has attracted relatively limited attention 10–16. This is somewhat surprising considering the substantial bandgap reduction in PTV (1.7 eV10, 14 compared to ∼2 eV for polythiophene6 and 2.5 eV for PPV9c), the relatively high hole mobility measured in OFETs based on PTV17 and its copolymers,18, 19 and the high conductivity in the doped state 20. One of the major drawbacks of PTV materials is the dramatic loss of emissive properties (quantum yield Φ PL ∼0.001% for parent PTV21).…”

Origin of high mobility within an amorphous polymeric semiconductor: Space-charge-limited current and trap distribution

“…Because amorphous characteristics prevent the formation of grain boundaries, thus enabling a high reproducibility of the device performances, 6 amorphous polymeric semiconductors are thought to be promising candidates for the fabrication of commercial OFETs, if it is possible to achieve a high FET mobility. Recently, the amorphous polymeric semiconductor polytriarylamine, 7 with a field-effect mobility close to 10 −2 cm 2 / V s, was reported by Veres et al In addition, we presented the amorphous semiconductor poly͓͑1,2-bis -͑2Ј-thienyl͒vinyl-5Ј ,5Љ-diyl͒ -alt-͑9,9-dioctyldecylfluorene-2,7-diyl͔, 8 which exhibited a relatively high and reproducible FET mobility ͑of over 10 −2 cm 2 / V s͒. However, in spite of their importance, no theoretical studies to elucidate the high FET mobility of amorphous polymeric semiconductors have been reported to date.…”

Investigating sensing properties of poly-(dioctylfluorene) based planar sensor

“…A variety of inherent properties of polyfluorene and its derivatives lead to the development of high molecular weight material with effective synthesis and purification [23]. Polyfluorenes have shown very promising performance in light emitting diodes (LEDs) [24,25] photovoltaic devices [26] and thin film transistors [27]. The poly (9,9-dioctylfluorene) (F8), which contains fluorine as a backbone, exhibits improved carrier mobility and optical characteristics by changing its phase [28,29].…”