Construction of effective organic solar cell using phenanthroline derivatives as cathode interface layer

Interface modification plays an important role in improving the efficiency of organic solar cells (OSCs). Here, disodium 4, 4'-(1,10-phenanthroline-4,7-diyl) dibenzenesulfonate (Phen-1) and disodium 4,7-diphenyl-1,10-phenanthroline 4′,4″-disulfonate (Phen-2) was successfully introduced into OSCs as cathode interface layers (CILs) using environment-friendly methanol as solvent. As contrasted with devices without (w/o) CILs, when Phen-2 as CIL, VOC of the devices increases from 0.73 V to 0.79 V, FF increases from 52.49% to 67.17%, respectively. Foremost, the power conversion efficiency (PCE) of the device has been improved from 5.56% to 8.58%. It was found that the surface of the active layer with CILs exhibited a smoother interface and better hydrophilicity, which facilitated the contact between the cathode and the active layer as well as the extraction and transport of electrons. This indicates that the use water-soluble phen series materials as CILs can improve device performance and provide an effective method for the preparation of environmentally friendly OSCs.