A bridged syn triphenylene derivative, namely 5,7-dihydroindeno[2,1-b]fluorene, functionalized with dicyanovinylene units (2,1-b)-IF( Q Q QC(CN) 2 ) 2 has been designed, synthesized and characterized. Its optical and electrochemical properties have been carefully studied through a combined experimental and theoretical approach and compared to those of three other structurally related dihydro[2,1-b]indenofluorene derivatives bearing methylenes,which possesses a very low LUMO level, ca. À3.81 eV, has been successfully used as an active layer in n-channel OFETs using an epoxy based photoresist SU-8 as the gate insulator. (2,1-b)-IF(Q Q QC(CN) 2 ) 2 based n-channel OFETs show promising properties such as a low threshold voltage functioning of 7.2 V (low gate-source and drain-source voltages), a high ratio between the on and the off currents (6.3 Â 10 5 ), interesting subthreshold swing (SS = 2.16) and electron mobility (410 À3 cm 2 V À1 s À1 ) and excellent stability under electrical stress. This electrical stability has allowed the incorporation of (2,1-b)-IF(Q Q QC(CN) 2 ) 2 based n-channel OFETs in an integrated circuit. Thus, as a proof of concept, pseudo CMOS inverters made of n-type (2,1-b)-IF( Q Q QC(CN) 2 ) 2 -based OFETs have been fabricated and characterized highlighting the potential of this new family of materials.View Article Online † † It should be mentioned that the trend is perfectly followed as the LUMO of (2,1-b)-IF(Q Q QO) 2 lies at À2.49 eV. ‡ ‡ As depicted below, TD-DFT calculations have allowed assigning the low energy band in (2,1-b)-IF(Q Q QO) 2 , (2,1-b)-IF(Q Q QO)(Q Q QC(CN) 2 ) and (2,1-b)-IF(Q Q QC(CN) 2 ) 2 to an HOMO/LUMO transition.
Drop on Demand inkjet printing is an attractive method for device fabrication. However, the reliability of the key printing steps is still challenging. This explains why versatile functional inks are needed. Epoxy based ink described in this study could solve this critical issue because it can be printed with low drawbacks (satellites droplets, long-lived filaments, etc.). Moreover, a wide concentration range of solute allows the fabrication of films from thin to high aspect ratio. Optimizing experimental parameters (temperature, overlap) and ink composition (single or cosolvent) is useful to tune the film profile. As a result, many shapes can be obtained such as donuts or hemispherical caps for a droplet and smooth or wavy shape for a thin film. This study demonstrates that epoxy based versatile ink can be used in numerous fields of applications (organic electronics, optics, sensors, MEMS, etc.). To prove this assertion, organic field effect transistors and light emitting films have been fabricated.
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