Effect of Branched Alkyl Ester-Labeled Side Chains on Specific Chain Arrangement of Diketopyrrolopyrrole-Based Conjugated Polymers and Their Thin Film Transistors
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초록
내용
Recently, many studies have focused on improving the carrier mobility in organic thin film transistors (OTFTs) by optimizing the size and bifurcation points of bulky branched alkyl chains on the conjugated backbone segments. However, there are limited studies related to the structures of DPP-based copolymers including alkyl side chains with polar functional units. In this presentation, six different DPP-based copolymers were demonstrated including DPP and bithiophene (BT) as electron-acceptor and donor backbone units, respectively, containing branched alkyl side chains, which were either directly coupled to the N-positions of DPP or separated by an alkyl ester group. It was found that the ester moieties form pseudo-hydrogen bonds with the nearest side chains in comparison to the alkyl-only system. The optimal DPP-based copolymer film showed the highest μ value of 2.30 cm2V-1s-1 in an OTFT, with a high on/off current ratio (Ion/Ioff ＞106).