title: Laterally expanded rylene diimides with uniform branched side chains for solution-processed air stable n-channel thin film transistors.
abstract: Molecular packing motifs in solid states is the dominant factor affecting the n-channel organic field-effect transistors (OFETs). However, few systematic researches were performed in the different extensions of π-conjugated molecules with the uniform substitution effecting the molecular packing motifs. In this manuscript, OFET devices based on three latterally expanded rylene diimides end-functionalized with uniform 3-hexylundecyl substitution on the imide positions were systematically studied on the relationship of molecular stacking, film microstructure, and charge transport. As the π-conjugated systems expanded from doubly linked perylene diimide dimer (d-4CldiPDI, 1), triply linked perylene diimide dimer (t-4CldiPDI, 2), to hybrid array (NDI-PDI-NDI, 3), their corresponding molecular packing motifs exhibited a divide: the optimized molecular configuration became more planar and d (001) spacing distances became larger, which resulted in a larger π-π overlapping. Thus, an enhanced electron mobility was obtained. A typical n-channel field-effect characteristic was observed in thin film devices based on these molecules under ambient conditions. Especially, the hybrid system (3) with more planar and π-expanded aromatic backbone exhibited superior electron mobility approaching 0.44 cm(2) V(-1) s(-1) and on/off ratio of 10(6) after optimal annealing in this study.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
authors.forename: Chengyi
authors.initials: C
authors.lastname: Xiao
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
authors.forename: Xiangguang
authors.initials: X
authors.lastname: Li
authors.forename: Linxiao
authors.initials: L
authors.lastname: Hao
authors.forename: Chunming
authors.initials: C
authors.lastname: Liu
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Wang
keywords: d-spacings; lateral expansion; molecular packing motifs; n-channel OFETs; rylene diimides; uniform branched side chains