The Stride Group - Discotic Liquid Crystals for Organic Conductor/Semiconductor Applications

Liquid crystals have become an integral part of modern life. They are used for displays in everything from computers to watches.

The most common of these liquid crystals are calamitic molecule based (rod shaped, see below).

Another form of liquid crystal which has been less well studied are discotics (disk shaped molecules) [1]. Discotics form columnar stacks. An electric current can pass through the stack via the cores of the molecules (download video) with higher efficiencies than most other forms of organic conductors [2].

Description of assembly of triphenylene core and pyrrole polymerisation

The nitrogen (blue atom) containing cyclic groups, known as pyrroles, are capable of polymerisation [3]. After polymerisation the structure of the liquid crystal is "locked in", creating a more stable organic conductor. The polymerisation will also potentially bring the cores of the triphenylene molecules closer together raising the conductivity of the core [4]. Polypyrrole is also an electrical conductor which can contribute to increased conductivity, given the good alignment of the polypyrrole chains.

The potential applications of this research include uses in flexible organic electronics such as organic light emitted diodes (OLED). This work also has the potential to be used in cheap and flexible photovoltaic devices, for example in solar panels [5].

 

References

 

  1. Sabine Laschat, Angelika Baro, Nelli Steinke et al., Angewandte Chemie International Edition 46 (26), 4832 (2007).
  2. D. Adam, P. Schuhmacher, J. Simmerer et al., Nature 371 (6493), 141 (1994).
  3. Michael Wolf, Journal of Inorganic and Organometallic Polymers and Materials 16 (3), 189 (2006).
  4. V. Lemaur, D. A. da Silva Filho, V. Coropceanu et al., J. Am. Chem. Soc. 126 (10), 3271 (2004).
  5. L. Schmidt-Mende, A. Fechtenkotter, K. Mullen et al., Science 293 (5532), 1119 (2001).

     

2D figures where constructed in Adobe Photoshop©. All other 3d images are constructed in Arguslab (ArgusLab 4.0, Mark A. Thompson, Planaria Software LLC, Seattle, http://www.ArgusLab.com) and Blender (Blender 2.44, open-source, http://www.blender.org)