Intermolecular n-Doping Nonconjugated Polymer Cathode Interfacial Materials for Organic Solar Cells

Three alcohol-soluble nonconjugated polymers poly [p-(N,N-dimethylamino)styrene] (PSN), poly[p-(N,N-dimethylamino)styrene] oxide (PSO), and poly[p-(N,N-dimethylamino)styrene] mesylate (PSM) were devised and synthesized for the application as cathode interlayers in the organic solar cells (OSCs) based on PBDB-T:IT-M. All of the polymers contain a highly polarized amino or ammonium group at the side chains, which can improve electron collection ability of the cathode interfacial layer of the OSCs. Both the amino and ammonium group with a negative ion of oxygen allow PSN and PSO to possess intermolecular n-doping effect with the IT-M acceptor at the interface. The understanding of the relationship between the n-doping effect and the cathode interlayer structures may offer additional insights to further develop novel cathode interfacial materials for OSCs.