The influence of numbers of subunits on the photovoltaic performance of non-fullerene acceptors

- Two new acceptors SF-2IIG and SF-4IIG were designed and synthesized.
- The effects of the number of the electron deficient building blocks on several characters were investigated.
- Increasing the numbers of IIG building blocks is beneficial to photovoltaic performance to achieve 220% enhancement.
- This result demonstrated a strategy of achieving high efficient non-fullerene solar cells.

Two new small-molecular acceptors SF-2IIG and SF-4IIG were designed and synthesized to investigate the influence of the numbers of electron-deficient subunits of non-fullerene acceptors on the efficencies of photovotaic devices. The studies showed that these two acceptors have different optical absorbption, energy levels, charge transport mobilities. As a result, the efficiencies of SF-4IIG based solar cells are significantly higher than those of SF-2IIG based ones.