A Dual Functional Diketopyrrolopyrrole-Based Conjugated Polymer as Single Component Semiconducting Photoresist by Appending Azide Groups in the Side Chains

Abstract

Molecular systems that can function as photoresists are essential for the fabrication of flexible electronics through all-photolithographic processes. Most of the reported molecular systems for photo-patterning of polymeric semiconductors contain binary or multi-components. In comparison, single component semiconducting photoresist is advantageous since it will circumvent the optimization of phase separation and ensure the patterned semiconducting thin films to be more uniform. In this paper, a single component semiconducting photoresist (PDPP4T-N3) by incorporating azide groups into the branching alkyl chains of a diketopyrrolopyrrole-based conjugated polymer is reported. The results reveal that i) the azide groups make the side chains to be photo-cross-linkable; ii) uniform patterns with size as small as 5 µm form under mild UV irradiation (365 nm, 85 mW cm−2) at ambient conditions; iii) such photo-induced cross-linking does not affect the inter-chain packing; iv) benefiting from the single component feature, field-effect transistors (FETs) with the individual patterned thin films display satisfactorily uniform performances with average charge mobility of 0.61 ± 0.10 cm2 V–1 s–1 and threshold voltage of 3.49 ± 1.43 V. These results offer a simple yet effective design strategy for high-performance single component semiconducting photoresists, which hold great potentials for flexible electronics processed by all-photolithography.