Alkylated-C60 based soft materials: regulation of self-assembly and optoelectronic properties by chain branching

Abstract

Derivatization of fullerene (C 60 ) with "branched" aliphatic chains can soften C 60 -based materials and enables the formation of thermotropic liquid crystals as well as room temperature nonvolatile liquids with tunable viscosity. The chain branching methodology with optoelectronic activity of C 60 is believed to be a powerful technique to develop C 60 -based soft and fl exible photovoltaic devices. As featured in:See H. Li et al., J. Mater. Chem. C, 2013, 1, 1943

Room Temperature Liquid Formulation by Attaching Alkyl Chains on ^|^pi;-Conjugated Molecules

“…10 This is mainly demonstrated by using two alkylated C 60 derivatives (13, 15) whose native liquid/amorphous state transformed into various assembled structures upon addition of additives favoring either segment of the molecules ( Figure 5). 6 For instance, addition of pristine C 60 directs the assembly into lamellar mesophases (d spacing around 3.6 nm) by increasing the proportion of C 60 part in the mixture (Figure 5c). The addition of n alkanes instead results in their assembly, due to the immiscibility of C 60 in n alkanes, into micelles (Figure 5d, average diameter 2.5 0.3 nm, polydisperse in size) and gel bers containing insulated C 60 nanowires ( Figure 5e, μm long; a hexagonally ordered columnar lattice in which the C 60 moieties are in the column centers).…”

“…7 Instead of the linear alkyl chains, branched alkyl chains and adjusting substituent position have been found to be more effective for lowering the viscosity of room temperature liquid C 60 . 6 For example, C 60 derivatives possessing two swallow tail type branched alkyl chains at the (3 ,5 ) (13; η 1500 Pa·s) or (2 ,5 ) (14; η 260 Pa·s) positions of the substituent phenyl unit (Figure 3b) show lower complex viscosity. According to the result, the ortho substituent position on the phenyl unit is more effective to produce lower viscosity liquid C 60 .…”

“…According to the result, the ortho substituent position on the phenyl unit is more effective to produce lower viscosity liquid C 60 . 6 These liquid fullerenes (5, 6, 8) are considered as pioneering molecular systems for the designing of room temperature liquid π conjugated molecules. 5 In addition to their liquid 5 This is maybe due to aggregation of the C 60 core units, as their interaction is only partially disturbed.…”

“…Therefore the proposed method can be considered as a novel self assembly technique that can be applicable to various π conjugated molecules in general. 10 Furthermore, both of the assembled lamellar mesophases and gel ber structure exhibit ordered C 60 derived photoconductivity, 10 which has charge transport properties comparable to leading solid crystalline C 60 derivatives including [6,6] phenyl C 61 butyric acid methyl ester (PCBM), 26,27 allowing free selection of the desired type of structure according to different applications.…”

Energy transfer in supramolecular materials for new applications in photonics and electronics

“…Chain branching was also evident in soft C 60 fullerenebased materials reported by the Nakanishi group. 51 In this case, the formation of various fullerene morphologies, including lamellar structures conducive toward two-dimensional energy and electron transport, were obtained by the use of branched alkyl chains ( Figure 4).…”