Thienoisoindigo-Based Semiconductor Nanowires Assembled with 2-Bromobenzaldehyde via Both Halogen and Chalcogen Bonding

Abstract

We fabricated nanowires of a conjugated oligomer and applied them to organic field-effect transistors (OFETs). The supramolecular assemblies of a thienoisoindigo-based small molecular organic semiconductor (TIIG-Bz) were prepared by co-precipitation with 2-bromobenzaldehyde (2-BBA) via a combination of halogen bonding (XB) between the bromide in 2-BBA and electron-donor groups in TIIG-Bz, and chalcogen bonding (CB) between the aldehyde in 2-BBA and sulfur in TIIG-Bz. It was found that 2-BBA could be incorporated into the conjugated planes of TIIG-Bz via XB and CB pairs, thereby increasing the π − π stacking area between the conjugated planes. As a result, the driving force for one-dimensional growth of the supramolecular assemblies via π − π stacking was significantly enhanced. TIIG-Bz/2-BBA nanowires were used to fabricate OFETs, showing significantly enhanced charge transfer mobility compared to OFETs based on pure TIIG-Bz thin films and nanowires, which demonstrates the benefit of nanowire fabrication using 2-BBA.

Benzothiadiazole Halogenation Impact in Conjugated Polymers, a Comprehensive Study

“…To start with the fluorinated polymer series, it is worth noting that solubility decreases with increasing number of fluorine atoms on the benzothiadiazole unit. This is due to the many weak bonds created between fluorine atoms and neighboring heteroatoms. − In practice, by lowering the temperature, the progressive aggregation of the polymer is observed and consequently, the UV–visible absorption of the solution is more and more similar to the one recorded for thin films. This is clearly observable for PF 2 that exhibits already at 65 °C and below (Figure c), typical thin film-like absorption spectra.…”

Bridging the Void: Halogen Bonding and Aromatic Interactions to Program Luminescence and Electronic Properties of π-Conjugated Materials in the Solid State

“…90 Among nanomaterials, a 2018 study from Noh et dehyde (XB donor) for the assembly of 1D nanowires that were used to construct OFET devices with favorable charge transport. 91 A related publication in 2020 from Koo et al demonstrated improved charge transport in a diketopyrrolopyrrole-dithienothiophene conjugated polymer by doping 2-bromobenzaldehyde (XB donor) to enhance through-space alignment of polymer backbones. 92 A series of studies from the group of Fabien Silly have described self-assembly of star-shaped oligophenylenes on metal and graphite where XX interactions can selectively pattern surfaces and tune band gap.…”

“…Among nanomaterials, a 2018 study from Noh et al. employed XB between a thienoisoindigo-based chromophore and 2-bromobenzaldehyde (XB donor) for the assembly of 1D nanowires that were used to construct OFET devices with favorable charge transport . A related publication in 2020 from Koo et al demonstrated improved charge transport in a diketopyrrolopyrrole-dithienothiophene conjugated polymer by doping 2-bromobenzaldehyde (XB donor) to enhance through-space alignment of polymer backbones .…”

Strong Bathochromic Shift of Conjugated Polymer Nanowires Assembled with a Liquid Crystalline Alkyl Benzoic Acid via a Film Dispersion Process

“…For example, charge transport efficiency in FETs can be significantly improved when conjugated backbones are assembled in one-dimensional (1D) nanowires, nanorods, or nanofibers due to the increased intermolecular charge transport. 27 − 29 In addition, intermolecular electron delocalization can narrow the band gaps of conjugated polymers, thereby enlarging the range of light absorption in the visible and NIR regions, thus enhancing light harvesting efficiency, which is useful when conjugated polymers are used as a photosensitizer in photocatalysis applications. 30 − 32 …”