Insight into thin-film stacking modes of π-expanded quinoidal molecules on charge transport property via side-chain engineering. Issue 8 (2nd February 2017)

• Record Type: Journal Article
• Authors: Zhang, Cheng; Yuan, Dafei; Wu, Hao; Gann, Eliot; Thomsen, Lars; McNeill, Christopher R.; Di, Chong-an; Zhu, Xiaozhang; Zhu, Daoben
• Is Part Of: Journal of materials chemistry. Volume 5:Issue 8(2017)
• Page Start: 1935
• Page End: 1943
• Publication Date: 2017-02-02
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c6tc05052b
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Control of molecular ordering and packing of π-conjugated molecules in the solid state is crucial for enhancing the charge transport properties in organic electronics. Abstract : Control of molecular ordering and packing of π-conjugated molecules in the solid state is crucial for enhancing the charge transport properties in organic electronics. A series of quinoidal materials based on different alkyl-chain branching positions on the thieno[3, 4- c ]pyrrole-4, 6-dione moiety flanked with unsymmetric thieno[3, 4- b ]thiophenes (2DQTT- n ) are synthesized. By the combination of organic thin-film transistor performances and thin-film characterization, we clarified the influence of the branching position on the film microstructure/molecular packing and charge transport properties. Air-stable solution-processable n-channel2DQTT- n derivatives show dramatic changes in film morphology and molecular packing, which leads to disparate electron mobilities ranging from ∼0.34 to 4.5 cm 2 V −1 s −1 .2DQTT-1 with a branching point at the two-position in the alkyl side chain results in a 3D molecular packing with a lamellate morphology, and an electron mobility of up to 4.5 cm 2 V −1 s −1 using an annealing temperature of just 80 °C. In contrast, the other three materials exhibit polymorphs and2DQTT-3 and2DQTT-4 even show mix-oriented crystallites which are highly disadvantageous to charge transport. These results demonstrate that variation of the alkyl-chain branching point is a powerful strategy to tune the stacking modes in the thin-film state, which enables high charge transport properties.