Synthesis of narrow bandgap random Isoindigo/Diketopyrrolopyrrole-based polymers containing thermally removable groups for Organic Field Effect Transistors

Abstract

A new series of narrow bandgap random conjugated polymers (RCPs) based on octyldedocyl-alkylated isoindigo and diketopyrrolopyrrole along with thermally removable tert-butoxycarbonyl groups to cast H-bonding upon heating up to 220 ℃ were synthesized successfully via Pd catalysed Stille cross-coupling methodology in high yields and reasonable molecular weights. As annealed polymer films (at 220 ℃ for 30 min) exhibited red-shifted UV-vis absorption spectra which reflected the improvement of crystalline structure. The formation of H-bonding in these polymers were studied using X-Ray diffractometry (XRD) measurements. In addition, the effect of H-bonding on the charge-carrier transfer behaviour was investigated. The results estimated from FETs showed that the crystalline structure of these random conjugated polymers obtained reasonable FET mobilities with 1.17 x 10-3 cm2 V-1s -1 for P(ODDPPT.BID) and 1.41 x 10-3 cm2 V-1s-1 for P(ODDPPT.BDPP).