Efficient organic solar cells achieved at a low energy loss

Organic photovoltaics(OPVs)have attracted much attention because of the advantages in low-cost and large-area fabrication and the great potentials in achieving flexible and semi-transparent devices(1)However,compared with inorganic and perovskite solar cells[2],OPVs show relatively low photoelectric conversion efficiencies,which is admittedly attributed to intrinsically low dielectric constants of organic materials[3]resulting in large energy losses(Eloss=EgqVoc,where Eg is the optical bandgap of the photoactive layer,Voc is the open-circuit voltage of photovoltaic devices and q is elementary charge).