Interface Engineering in High-Performance Low-Voltage Organic Thin-Film Transistors Based on 2,7-Dialkyl-[1]benzothieno[3,2-b][1]benzothiophenes

Abstract

We investigated two different (2,7-dialkyl-[1]benzothieno[3,2-b][1]benzothiophenes; C(n)-BTBT-C(n), where n = 12 or 13) semiconductors in low-voltage operating thin-film transistors. By choosing functional molecules in nanoscaled hybrid dielectric layers, we were able to tune the surface energy and improve device characteristics, such as leakage current and hysteresis. The dipolar nature of the self-assembled molecules led to a shift in the threshold voltage. All devices exhibited high charge carrier mobilities of 0.6-7.0 cm(2) V(-1) s(-1). The thin-film morphology of BTBT was studied by means of atomic force microscopy (AFM), presented a dependency upon the surface energy of the self-assembled monolayer (SAM) hybrid dielectrics but not upon the device performance. The use of C(13)-BTBT-C(13) on hybrid dielectrics of AlO(x) and a F(15)C(18)-phosphonic acid monolayer led to devices with a hole mobility of 1.9 cm(2) V(-1) s(-1) at 3 V, on/off ratio of 10(5), small device-device variation of mobility, and a threshold voltage of only -0.9 V, thus providing excellent characteristics for further integration.

High Mobility in Solution‐Processed 2,7‐Dialkyl‐[1]benzothieno[3,2‐b][1]benzothiophene‐Based Field‐Effect Transistors Prepared with a Simplified Deposition Method

“…We have compared the FET performances of devices prepared using bare SiO 2 or ozone-treated SiO 2 , both in a top-contact configuration. Although the untreated devices did not exhibit any noticeable gate response, for V G up to 100 V, the transistors treated with at least three cycles of UV/ozone exposure showed notably enhanced performances, in line with the results reported in the literature, [12,21,22] but without any additional treatment in the fabrication process. Figure 1 shows the transfer and the output curves of the selected devices.…”

“…These problems were somehow solved only by employing sophisticated multistep deposition techniques, cumbersome post-deposition treatments and dielectric surface functionalisations. [21,22] The use of these deposition processes relying on complex methods and numerous steps renders these OFETs less interesting for largescale applications.Herein, we report a simple procedure based on modification of the dielectric SiO 2 surface by exposing it to an intense UV/ ozone atmosphere, [23] which enables the fabrication of C12-BTBT-based OFETs featuring mobilities as high as 2.7 cm 2 V À1 s À1 . The synthesis of the molecule has been performed according to the literature.…”

“…These problems were somehow solved only by employing sophisticated multistep deposition techniques, cumbersome post-deposition treatments and dielectric surface functionalisations. [21,22] The use of these deposition processes relying on complex methods and numerous steps renders these OFETs less interesting for largescale applications.…”

High performance of rubrene thin film transistor by weak epitaxy growth method

“…To achieve better device performance, the improvement of organic film quality usually plays a vital role [8][9][10]. Generally, different substrates were used to grow active materials aiming at the improvement of film morphology and electronic structure of interface, and the increase of mobility in transistors is usually observed [11][12][13][14].…”

Improving the Performance of Organic Thin‐Film Transistors by Ion Doping of Ethylene‐Glycol‐Based Self‐Assembled Monolayer Hybrid Dielectrics

“…[ 18 ] The slightly reduced "overall performance" of transistors compared to devices with the same semiconductor but on other SAMs [ 16 ] can be attributed to the surface energy of the SAM which infl uences the semiconductor orientation and morphology at the interface which in turn directly infl uences the performance. [ 19,20 ] Additionally, the decrease of the absolute threshold voltage V th for the doped samples can be seen in Figure 3 c. V th of the reference sample is −2.91 V whereas the doping with potassium shifts it to −2.78 V, for lithium to −2.70 V, and for sodium to −2.68 V.…”