p-conjugated systems are used extensively in electronic devices. Self-assembly can be used as a simple method of organizing optoelectronically active p-conjugated molecules in a defined manner. One self-assembly route is to exploit low molecular weight gelators (LMWG) to form structures with precise control at both the nano- and micro-scale.  Gelation using suitably designed LMWG results from self-assembly of the gelator into well-defined one-dimensional structures, which then can entangle or cross-link. When the LMWG contain p-conjugated groups, this assembly leads to the stacking of these groups.The assembly of perylene bisimides (PBI) LMWG is of interest from the perspective of electronic materials, since perylene is an n-type material. PBIs have strong absorption, long fluorescence lifetimes and high quantum yields. There are a growing number of reports showing the formation of self-assembled wires and fibres from PBI-based LWMG.The optoelectronic performance of such materials can depend on both the chemical structure, but also on the morphology and uniformity of the aggregates formed.  Here, we show that amino acid-based PBIs can form one-dimensional structures at high pH and then gels at low pH. Both the dried solutions and dried gels are photoconductive. Interestingly, there is not a correlation between the absorption spectrum of the perylene group and the photoconductivity. We  explain here the importance of the irradiation wavelength. The photoconductivity does correlate with the formation of the radical anion, which is highly stable in air for many hours.

Photoconductive perylene bisimide gelators

248th National Meeting (2014)

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