n-Type Thin-Film Transistors Based on Diketopyrrolopyrrole Derivatives: Role of Siloxane Side Chains and Electron-Withdrawing Substituents

• DOI: 10.1021/acsami.9b18318
• Publication Date: 2019-12-16T11:00:18Z
• Authors: Suhendro Purbo Pr...; Sushil Kumar; San-Lien Wu; Guan-Ting Ciou; Yao-Jin Ke; Samala Venkateswarlu; Yu-Tai Tao; Chien-Lung Wang
• Keywords: HOMO/LUMO; Side chain; Siloxane

The physical properties, packing, morphology, and semiconducting performance of a planar π-conjugated system can be effectively modified by introducing side chains substituent groups, both which complementary to the π framework in changing intermolecular association, frontier molecular orbital energy, optical band gap, others. We herein show that installation end-capped electron-withdrawing groups (EWGs), such as dicyanovinyl (-DCV), 3-ethylrhodanine (-RD), 2-(3-oxo-indan-1-ylidene)-malononitrile (-INCN), together with siloxane backbones dithienyldiketopyrrolopyrrole (DPPT), DPPT-Si-DCV, DPPT-Si-RD, DPPT-Si-INCN, greatly improve its solubility, air stability, film morphology serve an n-channel thin-film transistor fabrication. EWGs attached DPPT core narrowed gap (Egopt) changed highest occupied lowest unoccupied energies (EHOMO ELUMO), making them suitable for field-effect (FET) applications. benefits include enhanced low crystallization barrier, enantiotropic phase behavior, much improved FET performance. DPPT-Si-INCN displayed low-lying HOMO (-5.82 eV) LUMO (-4.60 energy levels 1.22 eV, all suggest this derivative quite resistant toward aerial oxidation. Thin films these derivatives were prepared solution-shear method. A comparison solution-sheared indicated packing motif was somehow different from DPPT-Si-DCV π-π stacking tended align orthogonally shearing direction. This specific alignment could have impact on electron mobility (μe) values transistors based films.