Fig. 2

Synthetic routes and physicochemical properties of the acceptors. a Synthetic routes of MO-IDIC and MO-IDIC-2F, b absorption spectra of IDIC, MO-IDIC, and MO-IDIC-2F in chloroform solutions and films, c energy level diagram of the related materials used in the PSCs (the energy levels were measured by electrochemical cyclic voltammetry)