π-Conjugated oligomers based on aminobenzodifuranone and diketopyrrolopyrrole

Abstract

A new donor-acceptor type oligomer, named as O1 with aminobenzodifuranone (ABDF) capped at both ends of thiophene DPP, was synthesized and characterized. The amino groups (NH) in this oligomer react with the carbonyl units (CO) from the neighboring molecules forming hydrogen bonding (NH…OC), which results in hydrogen bonded oligomer O1. The thermal, optical, electrochemical, thin film properties as well as the density functional theory computational simulation of O1 were investigated. O1 thin film presented not only strong aggregation, but also hydrogen bonding association. This is beneficial for the charges to be carried across the individual molecules. The high HOMO levels of O1 (−5.31 eV) facilitate charge injection and ohmic contacts with electrodes. Apart from that, the good planarity backbone combined with strong D-A system for the π-conjugation of O1 is favorable for the intracharge transport. These properties provided the O1 thin film based organic field-effect transistors (OFET) with hole mobility (μh) of 0.28 cm2/V·s, and after annealing, the μh increased up to 0.39 cm2/V·s. Such hydrogen-bonding-mediated enhancement of π – π stacking exhibits potential for improving the performance of solution processable organic electronic materials. This work shows that the hydrogen bonding association is a simple and useful strategy to design π-conjugation oligomers for high performance OFETs.