My research group focuses on the chemistry and materials science of thiophenes, selenophenes and tellurophenes. We have recently developed selenophene-thiophene block copolymers and discovered that these copolymers undergo a significant amount of phase separation. This is surprising given the chemical similarity of the repeat units, however we have uncovered several properties, including crystal packing, that differ in these polyheterocycles. By suppressing crystallization we are able to achieve a solid-state morphology that is reminiscent of classical lamella-type micro structure that persists over a long range. In other work we have increased the compatibility of the selenophene and thiophene units and we observe co-crystallization in statistical copolymers. These statistical copolymers form nanowires and when fabricated into nanowire solar cells they operate with a greater efficiency than cells composed of homopolymer nanowires. We have also learned how to synthesize polymers and delocalized molecules based on tellurophene, and identified several unexpected properties in these materials including reversible binding of small molecules, and the ability to photo-reductively eliminate halogens including Br2, Cl2 and even F2. Recently we have been focusing on so-called ‘n-type’ organic materials. We have developed thionated perylene diimides and are applying these materials for transistors and as acceptors in singlet fission solar cells.