Producing p‐Doped Surface for Hole Transporting Layer‐Free Nonfullerene Organic Solar Cells

Abstract

Hole transporting layer‐free organic solar cells with simplified device structures are desirable for their mass production. In this work, a p‐dopant of organic molybdenum peroxide (OMP) to dope nonfullerene active layers to produce p‐doped surface on the active layer is adopted. The OMP can effectively dope widely used polymer donors of nonfullerene organic solar cells, i.e., PTB7‐Th, PBDB‐T, and even PBDB‐T‐2F that has a very deep highest occupied molecular orbital (HOMO) energy level of −5.47 eV. The doping mechanism lies in the strong oxidizing property of peroxide groups of the OMP leading to superior doping properties. In the end, hole transporting layer‐free nonfullerene organic solar cells with the device structure of ITO/PEI‐Zn/PBDB‐T‐2F:IT‐4F/Ag are fabricated. The cells show a power conversion efficiency of 12.2% and good thermal stability.