Narrow band-gap polymers

Lambert, XL. and J.P. Ferraris. 1991. Narrow band gap polymers Polycyclopenta[2,l-h 3,4-b] dithiophen-4-one. J Chem Soc Chem Commun 752. 

Arbizzani, C., et al. 1995. N- and p-doped polydithieno[3,4-k3, 4 -d]thiophene A narrow band gap polymer for redox supercapacitors. Electrochim Acta 40 1871. 

Havinga, E.E., W. ten Hoeve, and H. Wynberg. 1993. Alternate donor-acceptor small band-gap semiconducting polymers Polysquaraines and polycroconaines. Synth Met 55-57 299-306. Lambert, T.M., and J.P. Ferraris. 1991. Narrow band gap polymers Polycyclopenta[2,l-b 3,4-b ]dithiophene-4-one. / Chem Soc Chem Commun 752-753. 

Casado, J., R.P. Ortiz, M.C.R. Delgado, V. Hernandez, J.T.L. Navarrete, J.M. Raimundo, P. Blanchard, M. Allain, and J. Roncali. 2005. Alternated quinoid/aromatic nnits in terthiophenes building blocks for electroactive narrow band gap polymers. Extended spectroscopic, solid state, electrochemical, and theoretical study. / Phys Chem B 109 16616-16627. 

For the realization of narrow band gap polymers, a useful synthetic strategy consists in copolymerizing an electron-rich and an electron-poor unit, to obtain a donor-acceptor structure. An example of this alternating donor-acceptor architecture has been reported by Jenekhe [36] with the synthesis of the copolymer PNIBT consisting of an electron-donating dialkoxybithiophene and... 

The band gap governs the intrinsic electronic and optical properties of conjugated polymers. The design and synthesis of narrow band-gap polymers have been a challenge in the development of intrinsic polymeric semiconductors without doping. 

The first example of a narrow band-gap polymer is polyisothianaphthene [Structure (8)] with a band gap of near 1.0 eV [74,75]. Other polymers designed and synthesized with the intention of developing narrow band-gap polymers include poly(dithieno[3,4-b 3, 4 -d]thiophene [76], poly-4//-cy clopenta[2,1 -6 3,4-/ ]dithiophen-4-one [77], poly-4-dicyanimethy lene-4//-cyclopenta[2,l-6 3,4-6 ]dithiophene [78], poly(2,3-dihexylthieno[3,4-6]-pyrazine (9) [79], polysquaraines [80], polycroconaines [80], poly-(naphtho[2,3-c]thiophene-fl//-bithiophene) (10) [81], a polymer containing... 

Polysilanes are cr-conjugated polymers composed of Si-Si skeletons and organic pendant groups. They are insulators with filled intramolecular valence bands and empty intramolecular conduction bands. However, because of strong cr conjugation, they have rather narrow band gaps of less than 4 eV [24,25] and are converted to conductors by photoexcitation or by doping electron donors or acceptors. Recently they have attracted much attention because of their potential utility as one-dimensional conductors, nonlinear optical materials, and electroluminescent materials [26-28]. 

Di(2-thienyl)thieno[3,4-c][l,2,5]thiadiazole (178) has been polymerized to give a narrow band gap heterocyclic polymer with interesting optical and electrochemical properties <93SM1251>. Stable dithiazolyl radicals, such as (18) and (19), are useful as inhibitors and stabilizers for radical reactions <82EGP156366>. 

Thompson BC, Kim Y-G, Reynolds JR (2005) Spectral broadening in MEH-PPV PCBM-based photovoltaic devices via blending with narrow band gap cyanovinylene-dioxythiophene polymer. Macromolecules 38 5359... 

There are several reports on the exploitation of ferrocenyl moiety in the building up of polymetallaynes. A novel heterobimetallic platinum acetylide polymer of ferrocenylfluorene, P72, was reported and spectroscopically characterized.95 The presence of significant donor-acceptor interaction leads to a narrow band-gap value of 2.1 eV for this Pt-Fe mixed material, which is much lower than for the parent polymer, P25. The polymer is electroactive, with the half-wave potential of the ferrocene moiety slightly more anodic in P72 than in the diethynyl ligand precursor, which is in line with the transfer of electron density from the ferrocenyl donor unit to the electron-accepting Pt(II) center through the acetylide linkage. 

Lee, Y, et al. 2001. A new narrow band gap electroactive polymer Poly[2,5-bis 2-(3,4-ethylene-dioxy)thienyl silole]. Chem Mater 13 2234. 

Jenekbe, S.A. 1986. A class of narrow-band-gap semiconducting polymers. Nature 322 345-347. 

Li, X.Z., Y. Zhang, R.Q. Yang, J. Huang, W. Yang, and Y. Gao. 2005. Novel saturated red-emitting poly(p-phenylenevinylene) copolymers with narrow-band-gap units of 2,1,3-benzothiadiazole synthesized by a palladium-catalyzed stiUe coupling reaction. / Polym Sci Part A Polym Chem... 

Y. Xia, X. Deng, L. Wang, X. Li, X. Zhu, Y. Cao, An extremely narrow-band-gap conjugated polymer with heterocyclic backbone and its use in optoelectronic devices, Macromol. Rapid Commun., 27, 1260-1264 (2006). 

Low- or narrow-band-gap systems (gap <0.5 eV) already contain a high proportion of thermally excited electrons at room temperature. These materials can be oxidized electrochemically at a low oxidation potential to give conducting polymers. Conductivities up to lOS/cm are reached (after chemical or electrochemical doping) [13]. 

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