Design of indigo derivatives as environment-friendly organic semiconductors for sustainable organic electronics

Abstract

We report the synthesis and systematic investigation of nine different indigo derivatives as promising materials for sustainable organic electronics. It has been shown that chemical design allows one to tune optoelectronic properties of indigoids as well as their semiconductor performance in OFETs. Fundamental correlations between the molecular structures of indigo derivatives, structural characteristics of their films, charge carrier transport properties and transistor characteristics have been revealed. Particularly important was lowering the LUMO energy levels of indigoids bearing strong electron withdrawing groups which improved dramatically ambient stability of n-type OFETs. Chemical structures of novel indigoids enabling truly air-stable n-channel OFET operation were proposed.

5,5′-alkylsubsituted indigo for solution-processed optoelectronic devices

“…15 The group of Troshin reported a similar effect in the indigos substituted by halogens at the 5,5 0 -and/or 6,6 0 -positions. 16 These results indicate that in addition to changing the energy difference between the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO), the substituted functional group also plays a key role in the charge transport crucial for optoelectronic properties of indigos. The use of an alkyl chain as a substituent is a promising strategy for changing the crystal packing.…”

An iodine effect in ambipolar organic field-effect transistors based on indigo derivatives

“…10 In the present work, we show that introduction of iodine atoms, namely 5,5'diiodoindigo (4), remarkably improves the transistor properties. 10 In the present work, we show that introduction of iodine atoms, namely 5,5'diiodoindigo (4), remarkably improves the transistor properties.…”

“…10 V TH of 1 and 2 are estimated to be 19 V and 33 V, respectively. This is in agreement with the electronegative nature of 1 and 2.…”

“…9,10 Here, we show our data of crystal structures of 2 and 4 that are investigated by single-crystal X-ray structure analyses for comparison with the crystal structures of 1 and 3. 9,10 Here, we show our data of crystal structures of 2 and 4 that are investigated by single-crystal X-ray structure analyses for comparison with the crystal structures of 1 and 3.…”

Rational design of bio-inspired high-performance ambipolar organic semiconductor materials based on indigo and its derivatives

“…In particular, one of the halogenation compounds, 6,6 0 -dibromoindigo (also known as tyrian purple dye), has been reported with enhanced ambipolar charge carrier mobilities (l h /l e = 0.40/0.40 cm 2 V À1 s À1 ) [27]. Utilizing such chemical modification route, Troshin et al further systematically studied the effect of various electron-withdrawing groups (such as -F, -Cl, -Br, -CF 3 and -CN) at 5,5 0 -or 6,6 0 -positions of indigo on charge-transport properties of these derivatives [28]. However, the carrier mobilities of their derivatives are much lower (around 10 À5 -10 À2 cm 2 V À1 s À1 ) and the balanced charge transport vanishes, even unipolar charge transport has been observed.…”