Tailored Organic Nanoaggregates Generated by Self-Assembly of Designed Functionalised p-Quaterphenylenes on Muscovite Mica Substrates

Materials built up of π-conjugated molecular building blocks have seen a tremendous development recently due to their interesting optical, electrical and optoelectrical properties [1]. Studies of single molecule properties on the Ångstrom length scale have demonstrated the feasibility of molecular electronics [2] as bulk polymeric systems have proven the practicability of plastic electronics on the micrometer scale, which resulted in the first commercially available polymer-based light-emitting diodes already [3]. However, it is still a challenge to develop structures that are confined to the (sub)-wavelength nanometer regime in at least one or two dimensions [4]. Promising bottomup approaches have been developed using inorganic nanowires [5] or carbon nanotubes [6], however, the use of supramolecular self-assembly processes [7] of π-conjugated organic molecules is an attractive alternative to get access to defined shape-persistent objects under thermodynamic control. Although inorganic materials are usually chemically more stable, the use of organic rather than inorganic compounds to fabricate nanostructures usually has the advantage of higher luminescence efficiency at the same material density, more flexible spectroscopic properties, and in general easier and cheaper processing. Especially rod-like molecules [8] like oligothiophenes [1]b, [9], perylenes [10], pentacenes [11] and oligo-p-phenylenes [12, 13] have been studied in this context [14]. Among those the latter ones and especially the p-hexaphenylene has been found to form very interesting nanoaggregates upon vapour deposition on various solid supports using different deposition techniques [15–24].