Highly Ordered n/p-Co-assembled Materials with Remarkable Charge Mobilities

Abstract

Controlling self-organization and morphology of chemical architectures is an essential challenge for the search of higher energy-conversion efficiencies in a variety of optoelectronic devices. Here, we report a highly ordered donor/acceptor functional material, which has been obtained using the principle of ionic self-assembly. Initially, an electron donor π-extended tetrathiafulvalene and an electron acceptor perylene-bisimide were self-organized separately obtaining n-and p-nanofibers at the same scale. These complementary n-and p-nanofibers are endowed with ionic groups with opposite charges on their surfaces. The synergic interactions establish periodic alignments between both nanofibers resulting in a material with segregated and alternately stacked donor/acceptor nanodomains. Photoconductivity measurements show values for these n/p-co-assembled materials up to 0.8 cm 2 V -1 s -1 , confirming the effectiveness in the design of these heterojunction structures. This easy methodology offers great possibilities to achieve highly ordered n/p-materials for potential applications in different areas such as optoelectonics and photovoltaic.The control on the organization and morphology of organic materials at different scales is an essential challenge in current science. 1 In particular, organic materials employed for obtaining efficient photovoltaic devices require a controlled segregation of electron donor/acceptor domains in the active layers because transport of the photo-generated charge carriers occurs through these domains to the electrodes. This control over the organization of nanostructured domains at the same length scale generally results in an increase in conductivity or photoconductivity values. 2 One of the approaches to prepare optoelectronic materials for photon-energy conversion is the use of covalent donor-acceptor (D-A) dyads. In this context, a great variety of D-A dyads have been reported with an elaborated synthetic strategy. 3-5 These D-A dyads provide nanoscale D-A heterojunctions with different morphologies such as fibrous, 3 tubular 4 or liquid crystals, to name a few. 5 On the other hand, supramolecular chemistry is gaining attention, when compared to covalent methodologies, due to its higher versatility and easier ensembles preparation. From small molecules and through weak and non-covalent intermolecular interactions such as hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, π-π stacking and electrostatic interactions, it is possible to reach highly ordered structures at the nano and mesoscales. 6

Self-sorted photoconductive xerogels

“…6,29,30,56–58 However, to date studies have often used polychromatic light, 32,57 sacrificial electron donors, 24 or did not report the individual behaviour of the sub-components, 16 making it difficult to assess if an active heterojunction was indeed aiding the separation of photogenerated charges.…”

“…28 Martín and co-workers co-assembled a PBI and a tetrathiafulvalene into a hydrogel using opposing charges on the molecules. 29 They reported that the co-assembled structures give long lived separated charge states due to suppressed recombination. Another organogel based system utilised PBI and trithienylenevinylene LMWGs, again using a heat-cool method for self-assembly.…”

Very Facile Polarity Umpolung and Noncovalent Functionalization of Inorganic Nanoparticles: A Tool Kit for Supramolecular Materials Chemistry

“…Eur.J.2015, 21,14030 -14035 www.chemeurj.org As amphiphilic building blocks for the assembly of the second hydrophilic shell of [TiO 2 ÀPAC 16 ]@shell 1-7 next to the known surfactants 1 and 2,w es ynthesized as eries of new functional dendritic amphiphiles 3-7.C ompounds 3-5 consist of positively chargedp yridinium moietiesa st he core units and negativelyc harged carboxylates in the periphery.I nt hese prototypes, the opposite charges are separatedb yaseries of covalent bonds and organized within segregated areas of the macromolecular architectures. [9,20] Amphiphiles 1 and 2,c ontaining either ap ositive or negative singly charged head group were investigated for comparison and, in particular, as simple model amphiphiles to demonstrate the success of this supramolecular umpolung concept. At the isoelectricp oint, no additional counterions are required for charge neutralization.…”

Self‐Sorting in Supramolecular Assembly of π‐Systems

“…The atomic force microscopy images revealed coexistence of the long fibrillar structure for aggregate of 37 and the spherical nano‐objects for PCMB aggregate (Figure ). In a different approach, Martín and co‐workers reported ionic interaction mediated donor‐acceptor co‐assembly . They have used π‐extended tetrathiafulvalene (TTF) derivative as donor (38) and perylene diimide (PDI) derivative (39, 40) as acceptor where both contained ionic functional groups (Figure ).…”