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.