聚合物有机光伏的电荷产生机理

Polymer photovoltaics have achieved considerable development in recent years, and the latest Y-series non-fullerene acceptors represented by Y6 have boosted the power conversion efficiencies to nearly 20%, while some of their working mechanisms have not yet been fully understood. This paper reviews the research reports on the charge generation mechanism of polymer photovoltaic systems based on fullerene acceptors and non-fullerene acceptors in recent years, and compares the similarities and differences of the working mechanisms of the two systems and the possible reasons for the high performance of the Y series. Generally, the polymer donor-fullerene acceptor systems can achieve ultrafast charge separation, but suffers from large energy loss, which limits the improvement of their performance; the polymer donor-non-fullerene acceptor systems show greatly reduced energy loss, but their charge generation process is relatively slow, and in some cases the assistance of thermal energy is required. Y series acceptors have unique molecular packing way and charge generation kinetics which both contribute to their remarkable performance, while the specific mechanism of charge generation is still controversial. Also, possible methods and prospects for further reducing energy loss and improving device performance are proposed. It is clear that nonradiative recombination losses must be further reduced to achieve higher device performances, possibly by improving the photoluminescence quantum efficiency and fine-tuning the kinetics of the interconversion between excited state and charge transfer state. Finally, continuous efforts on improving the long term stability of polymer photovoltaic devices are still needed to promote their commercialization in the future.