Nonfullerene electron acceptors with electron-deficient units containing cyano groups for organic solar cells

Abstract

The performance of organic solar cells based on nonfullerene acceptors is improving rapidly and nowadays the power conversion efficiencies of single-junction devices have achieved over 18%. Nonfullerene acceptors usually consist of electron-rich units and electron-deficient units, and the interaction between these two parts can widen the optical absorption, tune the energy levels and improve the film morphologies of acceptor materials. Among the various electron-withdrawing groups, cyano groups have been most used in the construction of electron-deficient units for nonfullerene acceptors. In this review, the electron-deficient units containing cyano groups for nonfullerene electron acceptors have been summarized, and the effects of these electron-deficient units on the photoelectric properties and photovoltaic performance of acceptor materials have been elaborated to extract some effective molecular design strategies for high-performance acceptor materials.