Engineering Non-fullerene Acceptors as a Mechanism to Control Film Morphology and Energy Loss in Organic Solar Cells

Solution processable thin-film organic solar cells (TFOSCs) have attracted a lot of research attention in the past few decades, in the search for low-cost, flexible, and portable solar panels. In light of this, tremendous progress has been made in terms of improving materials design, device architecture, and ease of device fabrication processes. The choice of the donor and acceptor materials in the preparation of a polymer blend bulk heterojunction (BHJ) solar absorber medium is of great importance to the overall performance of organic solar cells (OSCs). The limitation in tuning the energy band structures of fullerene molecules poses significant challenges to the progress in BHJ organic solar cells. In an attempt to cater to the challenges, small-molecule non-fullerene acceptors (NFAs) came into the OSC research space with the possibility of altering the optoelectronic properties of the polymer molecules that bring OSCs closer to the realization of full-scale commercialization. This review discusses the role of NFAs in improving film morphology and reducing energy loss in TFOSCs. The recent development in engineering non-fullerene acceptors for solar energy conversion is presented and discussed in terms of reducing energy loss, improving solar cell performances.