Ladder Polymers as New Polymeric Conductors

Abstract

Abstract Electrical conductivity of heteroaromatic ladder polymers of the benzimidazobenzophenanthrolin type, BBL and BBB, and the phenothiazine type, PTL, was investigated. Doping studies of initially insulating BBL and BBB polymer films were carried out using various electron donors and acceptors. PTL polymer showed unexpectedly high conductivity (σ =10–5 ohm-1 cm-1); doping with ASF, brought about a minor increase in conductivity. With BBL and BBB polymers, a negligible doping effect was observed with halogens, a significant effect with AsF5 and a marked effect with SO3 (σ =1 × 10–2 ohm-1 can-1) and H2SO4 (σ =2 ohm-1 cm-1). A large increase of the thickness and the weight in the doped film is probably due to the planar layered structure of the polymers. The room temperature conductivity of potassium metal-doped (at 300–500°C) BBL film was 2 × 10–1 ohm-1 cm-1, while the potassium naphthalide-doped sample had a conductivity of 1 ohm-1 cm-1. In the acceptor-dopd samples, band broadening was observed in th...