ABSTRACT
Poly(3-hexylthiophene)-block-poly(3-(3-thioacetylpropyl) oxymethylthiophene) (P3HT)-b-(P3TT) diblock copolymers were synthesized and manipulated by solvent-induced crystallization to afford reversibly cross-linked semiconductor nanowires. To cross-link the nanowires, we deprotected the thioacetate groups to thiols and they subsequently oxidized to disulfides. Cross-linked nanowires maintained their structural integrity in solvents that normally dissolve the polymers. These robust nanowires could be reduced to the fully solvated polymer, representing a novel, reversible cross-linking procedure for functional P3HT-based nanowire fibrils. Field-effect transistor measurements were carried out to determine the charge transport properties of these nanostructures.
ABSTRACT
Self-assembled crystalline organic nanostructures containing electron donor and acceptor materials hold promise as building blocks for photovoltaic devices. We show that coupled crystallization of poly(3-hexyl thiophene) (P3HT) and perylene tetracarboxydiimide (PDI) induced by solvent evaporation, wherein both components modify crystallization of the other, gives rise to donor/acceptor "shish-kebabs" with tunable nanostructures. P3HT kinetically stabilizes supersaturated solutions of PDI and modifies the growth of PDI crystals, leading to formation of extended PDI shish nanowires that in turn serve as heterogeneous nucleation sites for fibrillar P3HT kebabs during solvent casting. The dimensions of these nanostructures can be tailored through variations in donor/acceptor ratio or solvent quality, and the method is shown to be general to several other poly(3-alkyl thiophenes) and perylene derivatives, thus providing a simple and robust route to form highly crystalline nanophase separated organic donor/acceptor assemblies.
Subject(s)
Imides/chemistry , Nanostructures/chemistry , Perylene/analogs & derivatives , Perylene/chemistry , Thiophenes/chemistry , Crystallography, X-Ray , Solvents/chemistryABSTRACT
Poly(3-hexyl thiophene) containing chain-end thiols or phosphonic acids is crystallized to yield nanowires with the functional groups at the wire edges. CdSe quantum dots and nanorods associate with these fibrils, leading to 'superhighways' that consist of alternating parallel lanes of conjugated polymer and CdSe.
Subject(s)
Ligands , Nanocomposites/chemistry , Polymers/chemistry , Semiconductors , Cadmium Compounds/chemistry , Nanocomposites/ultrastructure , Nanotubes/chemistry , Nanotubes/ultrastructure , Organophosphonates/chemistry , Phosphorous Acids/chemistry , Quantum Dots , Selenium Compounds/chemistry , Thiophenes/chemistryABSTRACT
We report wavelength and time-resolved photoluminescence studies of isolated extended (1-10 µm length) poly(3-hexylthiophene) (P3HT) nanofibers (xNFs) cast on glass from suspension. The PL spectra of xNFs show multiple vibronic replicas that appear to be associated with the existence of both H- and J-type aggregates. The PL spectra of xNFs made from regioregular (rr)- (93%) and highly regioregular (hrr)-P3HT (98%) both show similarities in PL spectra suggestive of common chain packing features, as well as subtle differences that can be attributed to higher long-range order in the hrr-xNFs. Specifically, PL spectral measurements on isolated xNFs made from highly regioregular (>98%) P3HT showed a red-shifted electronic origin (≈30 meV) and increased 0-0/0-1 PL intensity ratio for the J-type species, suggestive of enhanced structural coherence length and intrachain order.
