Role of Perfluorophenyl Group in the Side Chain of Small-Molecule n-Type Organic Semiconductors in Stress Stability of Single-Crystal Transistors

Abstract

Operational stability, such as long-term ambient durability and bias stress stability, is one of the most significant parameters in organic thin-film transistors (OTFTs). The understanding of such stabilities has been mainly devoted to energy levels of frontier orbitals, thin-film morphologies, and device configuration involving gate dielectrics and electrodes, whereas the roles of molecular and aggregated structural features in device stability are seldom discussed. In this Letter, we report a remarkable enhancement of operational stability, especially bias stress, of n-channel single-crystal OTFTs derived from a replacement of phenyl with perfluorophenyl groups in the side chain. Because of the several-molecule-thick single-crystal nature employed for the OTFTs, the crystal-surface properties are thought to be critical, where the surface structure composed of perfluorophenyl moieties could suppress interactions between environmental species and field-induced carriers owing to increased hydrophobicity and steric protection of π-conjugated units.

Selectively Fluorinated Furan‐Phenylene Co‐Oligomers Pave the Way to Bright Ambipolar Light‐Emitting Electronic Devices

“…NMR spectra ( 1 H, 13 C, and 19 F) were recorded with Bruker Avance-300, Bruker Avance-400 and Bruker Avance-500 spectrometers. Some 13 C NMR spectra were not recorded because of low solubility of the investigated compounds.…”

“…NMR spectra ( 1 H, 13 C, and 19 F) were recorded with Bruker Avance-300, Bruker Avance-400 and Bruker Avance-500 spectrometers. Some 13 C NMR spectra were not recorded because of low solubility of the investigated compounds. IR spectra were recorded with a Bruker Tensor 27 FT-IR spectrometer in potassium bromide pellets (concentration ≈ 0.25%, pellet thickness ≈ 1 mm).…”

“…[18] in order to activate the intermediate and turn the equilibrium to the formation of desired products: 2,2″-(1,4-phenylene)bis [5-(pentafluorophenyl)furan] (F5-FP5) or 2,2′-(2,3,5,6-tetrafluoro-1,4-phenylene)bis [5-(pentafluorophenyl)furan] (F5-FP F 5). The synthesized compounds were characterized by 1 H, 19 F, 13 C NMR, IR, HRMS spectroscopies and elemental analysis (Figures S1-S25, Supporting Information).…”

“…[1d,11] The introduction of perfluorophenyl groups also enhanced the operational stability of organic field-effect transistors (OFETs) assigned to the increased hydrophobicity and steric protection of π-conjugated units. [13] Previously synthesized and comprehensively investigated 1,4-bis(5-phenylfuran-2-yl)benzene (FP5, Scheme 1) seems a perfect platform for subsequent modification and investigation of fluorinated FPCOs because of its high solubility and molecular rigidity, bright luminescence, long exciton diffusion length, and efficient hole transport. [5,8] As fluorination of the furan moiety is a significant synthetic challenge, there is a wide possibility to combine fluorinated phenyl(-ene) groups in FP5.…”

Near-IR Absorbing Molecular Semiconductors Incorporating Cyanated Benzothiadiazole Acceptors for High-Performance Semitransparent n-Type Organic Field-Effect Transistors

“…TCNBT Th IDT exhibits an electron mobility that reaches μ e,sat,max ≈ 1.1 cm 2 V −1 s −1 in this device architecture, which to the best of our knowledge, is one of the highest reported for spin-cast n-type small molecules in undoped devices. 15,49,50 The device exhibited reasonable characteristics with an on/off current ratio I on/off ≈ 10 3 to 10 4 and a threshold voltage V T ≈ 33 V (Table 2). Notably, the square root plot of the drain current was linear, with no evidence of the device nonidealities apparent in some highmobility devices.…”