Fused ring A–DA′D–A (Y-series) non-fullerene acceptors: recent developments and design strategies for organic photovoltaics

Abstract

In this review, we aim to explore the structure–property relationships of a library of Y-series non-fullerene acceptors (NFAs), their current advances, and present systematic (chemical modification) understanding, which have led to the development of effective electron acceptors for use in organic solar cell (OSC) applications. NFAs are a new field, where Y-series acceptors a have greater performance than other NFAs. Herein, we review the representative identities of the active layers of Y-series NFAs and their corresponding morphology, which can be tuned by adjusting various structural parameters such as their center donor core, side chains, and terminal acceptor end groups. This review focuses on various processing techniques including thermal annealing and special additives, solvents, and process conditions used to improve the efficiency of organic Y-series NFAs toward highly efficient and stable OSCs. We also highlight the opportunities made possible by the Y-series NFAs by outlining the challenges and future development directions of OSCs.