Conjugated materials containing dithienometalloles

Abstract

The development of new semiconducting conjugated polymers has been an important aspect of plastic electronics research since the early days of the field, as it allows the optoelectronic properties to be tuned for various applications. Dithienometalloles, which consist of a 2,2’-bithiophene fused with a bridging heteroatom, have been an important class of monomers for some time. The heteroatom serves an important role, both in holding the bithiophene unit rigidly coplanar and also in tuning the energetics of the system. In addition, these moieties often possess alkyl chains located on the bridging heteroatom that serve to confer solubility and processability to the final polymers. In this thesis we report the synthesis and properties of a number of dithienometallolecontaining polymers, in which the necessary solubilising groups have been moved from the bridging heteroatom to the adjacent thiophene backbone of the dithienometallole. This enabled the preparation of novel, soluble arsole-containing conjugated polymers. These dithienoarsole containing materials were used in both organic field effect transistors and organic photovoltaic devices, showing promising performances as well as significantly improved air stability over their phosphorus-containing analogues. The effect of changing the bridging heteroatom in dithienometalloles was also studied by comparing the optoelectronic properties and device performances of polymers with carbonyl, silicon, germanium, and nitrogen bridging groups. Finally, dithienopyrrole-based sensors were developed that showed substantial colour changes on exposure to basic solutions, as well as potential for use as readily dopable materials for electronic applications.