Typically, organic molecules are deposited from solution on surfaces using simple procedures like spin-coating or drop-casting. The obtained films are usually poorly uniform as they feature a low degree of order on the mesoscopic scale.
We develop new techniques to process organic materials from solution, and self assemble them in orrdered structures having size from few nm to one millimeter. Materials processed range from polyaromatic molecules, to polymers, to fullerenes and graphenes.
In particular, we demonstrate that solvent vapor annealing (SVA) can be used to tailor millimeter long fibers or mesoscopic crystals starting from disordered perylenes or hexabenzocoronenes layers. The SVA process, whose mechanism is governed by nucleation, features both a long-range mass transport of the molecules over hundreds of microns distances, and a reversible character as obtained by changing the solvent, allowing thereby to switch the material morphology from ordered fibers to amorphous droplets. In view of its versatility proven by the use on different molecules, substrates and solvents, SVA can be regarded as a new, general method to self-assemble molecular-based architectures for application in material science.
1. R. Dabirian, V. Palermo, A. Liscio, E. Schwartz, M.B.J. Otten, C.E. Finlayson, E. Treossi, R.H. Friend, G. Calestani, K. Mullen, R.J.M. Nolte, A.E. Rowan, and P. Samorii, The Relationship between Nanoscale Architecture and Charge Transport in Conjugated Nanocrystals Bridged by Multichromophoric Polymers. Journal of the American Chemical Society, 2009, 131, 7055.
2. G. De Luca, A. Liscio, P. Maccagnani, F. Nolde, V. Palermo, K. Mullen, and P. Samori, Nucleation-governed reversible self-assembly of an organic semiconductor at surfaces: Long-range mass transport forming giant functional fibers. Advanced Functional Materials, 2007, 17, 3791.
3. V. Palermo and P. Samori, Molecular self-assembly across multiple length scales. Angewandte Chemie-International Edition, 2007, 46, 4428.
4. E. Treossi, A. Liscio, X.L. Feng, V. Palermo, K. Muellen, and P. Samori, Temperature-Enhanced Solvent Vapor Annealing of a C-3 Symmetric Hexa-peri-Hexabenzocoronene: Controlling the Self-Assembly from Nano- to Macroscale. Small, 2009, 5, 112.