N-Cyanoimine as an electron-withdrawing functional group for organic semiconductors: example of dihydroindacenodithiophene positional isomers

Abstract

This work focuses on a detailed structure–property relationship study, including the incorporation in n-type OFETs, of two dihydroindacenodithiophene regioisomers bearing two cyanoimine groups either in a syn- or an anti-configuration.

[4]Cyclo‐N‐ethyl‐2,7‐carbazole: Synthesis, Structural, Electronic and Charge Transport Properties

“…Finally,i no rdert od etermine the charge transportp roperties, [4]C-Et-Cbz has been used as activel ayer in p-type channel OFETsp ossessing ab ottom-gate bottom-contact (BG-BC) architecture (device structure [56,57] in Figure S41). This BG-BC structure, in which the active layer is evaporated in the last step, avoids any structurale ffect resultingf rom the deposition of other layers.I ts hould be mentionedt hat [4]C-Et-Cbz can be easily evaporated (230 8C, 2.10 À7 mbar).O FET characterization provides am obility m FE of 1.1 10 À5 cm 2 V À1 s À1 ,athreshold voltage (V TH )o f2 4V ,asubthreshold swing (SS)o f2 .2 Vdec À1 and an on/off ratio of the drain current (I Don /I Doff )o f4 .26 10 4 , Figure 5.…”

“…Finally, in order to determine the charge transport properties, [4]C‐Et‐Cbz has been used as active layer in p‐type channel OFETs possessing a bottom‐gate bottom‐contact (BG–BC) architecture (device structure in Figure S41). This BG–BC structure, in which the active layer is evaporated in the last step, avoids any structural effect resulting from the deposition of other layers.…”

The influence of alkyl group regiochemistry and backbone fluorination on the packing and transistor performance of N-cyanoimine functionalised indacenodithiophenes

“…This feature was also present for the non-fluorinated analogue (2,7-dihexyl-IDT-di(N(CN))), as previously reported by Rault-Berthelot et al, though this feature was not explicitly discussed. 39 The T d of 364 1C reported for 2,7-dihexyl-IDT-di(N(CN)) was 440 1C higher than for 2,7-dihexyl-diFIDT-di(N(CN)) (T d = 321 1C), indicating that core fluorination was detrimental for the thermal stability. Repositioning of the hexyl chains from 2,7-position to 3,8-position led to a small increase in thermal stability (13 1C).…”

“…[36][37][38] Recently, Rault-Berthelot and co-workers reported that IDT functionalised with N-cyanoimine exhibited a very similar LUMO level to IDT functionalized with dicyanomethylene, thereby demonstrating its strongly electron-withdrawing nature. 39 Building upon these results, we hereby report the synthesis and characterization of two novel fluorinated IDT derivatives (diFIDT-di(N(CN))) containing the N-cyanoimine group. In addition, we also investigate how changing the regiochemistry of the required solubilizing hexyl group from the alpha (2,7-) to the beta (3,8-) positions of the IDT core influences solid-state packing and device performance.…”

“…Electrochemical data for 2,7-dihexyl-IDT-di(N(CN)) was taken from Rault-Berthelot and co-workers, where E 1/2 for the first reduction peak was extracted to provide a better comparison. 39 No major differences in the cyclic voltammograms were observed between dialkyl-diFIDT-di(N(CN)) analogues in solution, reflecting the negligible impact of alkyl chains on the electrochemical properties. The cyclic voltammograms displayed two chemically reversible reductions along with one or two irreversible oxidations (Fig.…”