<p>Organic solar cells (OSCs) are no longer based on fullerene acceptors but instead on a newer form of non-fullerene acceptor (NFA). NFAs have significantly increased the power conversion efficiencies of OSCs, typically showing improvements ranging from 2.5% to 18% over fullerene-based devices.Such advantages of NFAs as the modifiable optical bandgaps, improved transport of charge and broad absorption spectra, can be attained effortlessly with synthesis variation methods and by simply altering chemicals. In this review, new developments in high-performance NFAs are discussed, including designing donor and acceptor materials in an intelligent fashion, control of the shape of blends and device construction. Also discussed in the review are how to ensure devices are more stable and can grow by the use of NFAs. In tandem designs, more sub-cells are connected which better utilizes the solar spectral range and reduces energy loss. It also discusses issues related to commercializing scaled OSCs and the future of materials and device engineering research.</p> Graphical Abstract <p></p>