Amphiphilic Molecular Design as a Rational Strategy for Tailoring Bicontinuous Electron Donor and Acceptor Arrays: Photoconductive Liquid Crystalline Oligothiophene–C60 Dyads

Tailoring bicontinuous electron donor (D) and acceptor (A) arrays in solution-processable materials is an essential step for the realization of thin-film organic optoelectronics.1 Casting of a D/A mixture may give rise to photoconductive bulk materials.2 However, without proper choice of the components, many defects are usually formed, leading to trapping and rapid annihilation of charge carriers. In view of photovoltaics, the presence of bicontinuous D and A arrays is essential, but cast films from D/A mixtures likely contain their charge-transfer complexes. So far, nanofibers and tubes with bicontinuous D and A arrays have been obtained by self-assembly of covalently linked D-A dyads.3,4 Nevertheless, solution-processable bulk materials with a D/A heterojunction5 might be more realistic for device applications. Here we report a photoconductive liquid crystal (LC) with bicontinuous arrays of densely packed D and A components, tailored from amphiphilic oligothiophene-C60 dyad 1Amphi (Chart 1).6 Together with contrasting results for a nonamphiphilic reference (1Lipo), we highlight a crucial role of the amphiphilic design both in structuring and in photoconductivity.