A Dual Functional Diketopyrrolopyrrole-Based Conjugated Polymer as Single Component Semiconducting Photoresist by...

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.