Conjugated polymers based on selenophene building blocks

The intrinsic flexibility, solution processability, and optoelectronic properties of semiconducting conjugated polymers make them ideal candidates for use in a wide range of next-generation electronic devices. A virtually unlimited chemical design space has led to diverse polymeric architectures made from combinations of smaller molecular building blocks with desirable functionalities. Of these, thiophene is undoubtedly the most common due to its mixture of synthetic versatility, polymer backbone planarizing effects, and good optoelectronic characteristics. However, the success of thiophene has meant that other heterocycles, such as selenophene, remain relatively underexplored. This focus review discusses the challenges and material advantages of incorporating selenophene into conjugated polymer systems within the context of our contributions to the field. The early studies of poorly performing electrochemically synthesized polyselenophenes are outlined, progressing onto the model chemically synthesized alkylated homopolymers that revealed the key consequences of selenophene addition. We then review the various donor and donor-acceptor copolymer strategies that have exploited the properties of the selenium atom to enhance the performance of solar cells, transistors, and other organic electronic devices. Finally, we give our perspective on the state of the field and the fundamental material optimization studies required to realize the full potential of selenophene-containing conjugated polymers.