title: Alkyl-πengineering in state control toward versatile optoelectronic soft materials.
abstract: Organicπ-conjugated molecules with extremely rich and tailorable electronic and optical properties are frequently utilized for the fabrication of optoelectronic devices. To achieve high solubility for facile solution processing and desirable softness for flexible device fabrication, the rigidπunits were in most cases attached by alkyl chains through chemical modification. Considerable numbers of alkylated-πmolecular systems with versatile applications have been reported. However, a profound understanding of the molecular state control through proper alkyl chain substitution is still highly demanded because effective applications of these molecules are closely related to their physical states. To explore the underlying rule, we review a large number of alkylated-πmolecules with emphasis on the interplay of van der Waals interactions (vdW) of the alkyl chains andπ-πinteractions of theπmoieties. Based on our comprehensive investigations of the two interactions' impacts on the physical states of the molecules, a clear guidance for state control by alkyl-πengineering is proposed. Specifically, either with proper alkyl chain substitution or favorable additives, the vdW andπ-πinteractions can be adjusted, resulting in modulation of the physical states and optoelectronic properties of the molecules. We believe the strategy summarized here will significantly benefit the alkyl-πchemistry toward wide-spread applications in optoelectronic devices.
authors.affiliation: International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS) 1-2-1 Sengen, Tsukuba 305-0047, Japan.
authors.forename: Fengniu
authors.initials: F
authors.lastname: Lu
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakanishi
keywords: alkyl chains; liquid; optoelectronic; self-assembly; π-conjugated molecules