Efficient ternary active layer materials for organic photovoltaics

In recent years, ternary organic solar cells (OSCs) emerged as a potential candidate in photovoltaic-technology to constantly refresh the devices' power conversion efficiency (PCE). The introduction of ternary components (polymer or small molecule) proved a facile and practical approach to overcome the performances of binary-OSCs, increased mechanical-flexibility, provided ease in fabrication, made them light-weight, and mutually combined the merits of single-junction and tandem solar cells. Recently, the insertion of small molecule and non-fullerene acceptors into the binary blend is considered a most promising strategy to fabricate highly efficient ternary OSCs devices. To date, the PCE has reached 19%, that opened the track for the commercialization of OSCs. In this review article, we will firstly present basic working principles of ternary OSCs, followed by recent trends and strategies settled for selecting ternary-components. For ternary architecture, we discussed the basic role of third-component, progress and prospect of non-fullerene acceptors, solution-processed non-fullerene acceptor, morphology optimization, the ratio of each component, and the miscibility of nanostructure. Then we summarize the key progresses achieved with different types of ternary OSCs based on polymer, small molecules (SMs), and non-fullerene acceptors (NFAs). At end, we deduce with a summary and challenges of different types of ternary OSCs.