A Class of Narrow Band Gap Semiconducting Polymers.
HONEYWELL INC BLOOMINGTON MN PHYSICAL SCIENCES CENTER
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Scientific interest in electrically conducting polymers and conjugated polymers in general has been widespread, and continues to grow, among workers in polymer science, chemistry, condensed matter physics, materials science, andj related fields since the discovery of doped conductive polyacetylene. Numerous doped conducting organic polymers with conductivity spanning the insulator to near metallic range approx. 10 to the -15th power to 1,000ohmcm are not known. Of prime importance and fundamental interest in the continuing experimental and theoretical search for new conducting, and perhaps superconducting, polymers is achievement of small or vanishing semiconductor band gap E sub g which governs the intrinsic electronic, optical, and magnetic properties of materials. Existence of a finite E sub g in conjugated polymers is thought to originate principally from bond-length alternation which is related to the Peierls instability theorem for one-dimensional metals. Here we describe a novel class of conjugated polymers containing alternating aromatic and quinonoid segments whose members exhibit intrinsic band gaps as low as 0.75 ev, the smallest known value of E sub g for organic polymers. The idea that introduction of quinonoid character into a polymer main chain could lower the band gap is experimentally demonstrated and the effect described in terms of molecular parameters and bond-length alternation. Keywords Narrow band gap organic semiconductors.
- Solid State Physics