Toward Organic Photovoltaic Cells Based on the Self-Assembly of Discotic Columnar Liquid Crystals

Abstract

Two key parameters for the performance of an organic photovoltaic cell are the exciton diffusion length and the charge carrier mobility. Considering these parameters, columnar liquid crystals, with strong pi-orbital overlap between neighbouring cores, are promising materials. We describe our strategy towards the synthesis of both donor- and acceptor-type materials exhibiting a hexagonal columnar mesophase at the operating temperature range of the cell, including room temperature. We present the alignment behaviour of these materials when submitted to a thermal annealing, and, in particular, an approach to obtain thin open films with homeotropic orientation.

Keywords:

• Columnar liquid crystals
• discotic molecules
• donor–acceptor materials
• photovoltaic devices
• pi interactions
• solar cells