The correlations between semiconductor type and gas sensing properties in soluble acene/polymer blends have not yet been examined. Here, the phase separation mechanism in pseudo-liquid phase blend film is investigated and an unusual solid-state morphology that is effective for amperometric gas sensing performance is demonstrated. In 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS–pentacene)/poly(fluorine-co-triarylamine) (PTAA) blend, two phases are uniformly mixed, without being completely phase-separated due to the similar solubility and surface tension. On the other hand, in 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene (diF–TES ADT)/PTAA blend, the diF−TES ADT molecules are segregated both at the air–film, and film–substrate interfaces, and subsequently crystallized with a high degree of crystal perfection. In the meanwhile, Marangoni-flow induces crater-like via hole structure of PTAA at the middle layer. In situ measurement of (ultraviolet–visible) UV–vis absorption spectra and computational calculation reveal kinetics of liquid–solid–crystal transition in relation to the functional groups of soluble acene. Interestingly, flow driven hole structure of PTAA in diF–TES ADT/PTAA blend film allows the target NO2 gas to selectively penetrate the channel region, thereby enhancing sensitivity toward NO2, while decreasing affinity with other gases. The results provide protocols for fabricating highlperformance field-effect transistors and gas sensors in a blending system.
|Journal||Advanced Functional Materials|
|State||Published - Jul 11 2023|
Bibliographical noteFunding Information:
This work was supported by Korea Institute for Advancement of Technology (KIAT) grant funded by the Korea Government (MOTIE) (P0012770) and grant from the Basic Science Research Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2023‐00208902).
2,8‐difluoro‐5,11‐bis(triethylsilylethynyl) anthradithiophene (diF−TES ADT) and 6,13‐bis(triisopropylsilylethynyl) pentacene (TIPS–pentacene) were synthesized and provided by the Anthony groups, with support from the National Science Foundation under Cooperative Agreement No. 1 849 213. Poly(triaryl amine) (PTAA) was purchased from Ossila, and 1,2‐dichlorobenzene was purchased from Sigma Aldrich Co. A silicon wafer containing thermally grown SiO (thickness of 300 nm) was purchased from Fine Science. The diF−TES ADT/PTAA (1:1 w/w) blended solutions (20 mg mL) and TIPS–pentacene/PTAA (1:1 w/w) blended solutions (20 mg mL) were spin‐cast onto the SiO/Si substrates at 1000 rpm s for 80 and 50 s, respectively (at room temperature (RT), and in ambient air). After the spin coating was completed, the samples were immediately placed in separate Petri dishes, and wrapped with aluminum foil to prevent light illumination, and to induce slow evaporation of the solvent in ambient air. For the top‐contact OFET devices, Au source–drain electrodes (channel length: 100 µm and width: 2000 µm) were thermally evaporated through a shadow mask. After the source and drain electrodes deposition, each device was electrically isolated by a mechanical scratch. The Ag wires at each source and drain electrodes were electrically wired to characterize the gas sensor. To selectively remove the diF−TES ADT and TIPS–pentacene layers, the diF−TES ADT/PTAA and TIPS–pentacene/PTAA blend films were immersed in ‐hexane for one day. 2 −1 −1 2 −1 n
© 2023 Wiley-VCH GmbH.
- Marangoni flow
- gas sensors
- organic field-effect transistors
- phase separation
- soluble acene/PTAA blends
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Chemistry (all)
- Materials Science (all)
- Condensed Matter Physics