Controlling Rigidity and Planarity in Conjugated Polymers: Poly(3,4-ethylenedithioselenophene (original) (raw)
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Poly(3,4-ethylenedioxyselenophene
Journal of The American Chemical Society, 2008
Since the discovery of highly conductive iodine-doped polyacetylene, 1 conducting polymers 2 have become a rapidly growing field in chemistry. However, despite significant efforts, the types of conducting polymers are limited to polythiophenes, polypyrroles, polyacetylenes, polyphenylenes, poly(p-phenylene vinylene)s, and a few others. Given the similarity between thiophene and selenophene rings, and considering that selenium analogues of tetrathiafulvalene (TTF), such as tetramethyltetraselenafulvalene (TMTSF) and bis(ethylenedithio)tetraselenafulvalene (BETS), have been shown 3 to be even better organic superconductors than TTF derivatives, it is surprising that very little is known about polyselenophenes and no highly conductive polyselenophene was reported. 4,5 Theoretical studies 6 indicate that polyselenophenes should have a lower band gap than polythiophenes. Polyselenophenes are also expected to have some advantages over polythiophenes, such as having lower oxidation and reduction potentials, 6 being easier to polarize (since the selenium atom is more easily polarized than sulfur), and being more suited to interchain charge transfer (which should be facilitated by intermolecular Se · · · Se contacts).
Journal of Materials …, 2012
In this work, we prepared a series of new conjugated polyselenophenes that, in the 3,4-positions of the selenophene ring, have oxygen or sulfur substituents bridged by a phenylene moiety. Such substitution of a conjugated backbone produces a skeleton that has only planar units, does not have stereo centers, and offers the potential to structurally modify the polymer without impairing its conjugation. The reported polyselenophenes exhibit significantly different properties as a function of the heteroatom. The selenophene backbone combined with a phenylene periphery creates the rare combination of a lowband gap, low HOMO energy level, and a flat skeleton, which is desired for many optoelectronic applications. The properties of the phenylene-bridged polyselenophenes were compared with those of their polythiophene analogs. The polyselenophenes obtained in this work have a lower band gap and higher planarity than polythiophenes and their monomers electropolymerize more easily. Theoretical studies support the experimental findings about rigidity and band gap changes.
Synthetic Metals, 2020
Recently, significant efforts have been devoted on poly(3,4-ethylenedioxyselenophene) (PEDOS) and its derivatives due to their promising properties for various optoelectronic applications. Surprisingly, no study has been reported on electrochemical synthesis of PEDOS on flexible substrate, and its optoelectronic properties. In this work, electropolymerization of 3,4-ethylenedioxyselenophene (EDOS) on flexible (ITO/PET) as well as rigid (ITO/glass) substrates, followed by cyclic voltammetry, electrochemical stability, morphology, spectroelectrochemical, and electrochromic properties of the PEDOS films were studied. For comparison purpose, poly (3,4-ethylenedioxythiophene) (PEDOT) films were also prepared on both flexible and rigid substrates and a throughout comparison was made. It has been observed that the polymer films on flexible substrates are relatively more stable, rough, and show blue shift in absorption spectra as compared to the polymer films on rigid substrates. On repeated bending, polymers films on flexible substrate exhibits good mechanical stability. Moreover, polymer film on flexible substrate has improved contrast ratio than that of polymer film on rigid substrate, whereas no significant change of response time has been observed. To the best of our knowledge, electropolymerization of EDOS on flexible substrate has been reported for the first time.
Organic Electronics, 2005
In this report regioregular poly(3-alkylthiophenes) (P3ATs) (P3HT: poly(3-hexylthiophene, P3OT: poly(3-octylthiophene, P3DDT: poly(3-dodecylthiophene) were studied regarding their optical and electrochemical properties and used as electron donors in polymer solar cells. The optical band gap energy for the three polymers amounts to 1.92 eV. With longer side chain length their electrochemical band gaps are slightly increased, whereas the absorption coefficient undergoes a systematic decrease. The absorption spectra of the pristine P3ATs exhibit a distinctive blue shift of the p-p* interband transition upon mixing with PCBM 1:3 (as prepared films; P3HT: 45nm,P3OT:45 nm, P3OT: 45nm,P3OT:85 nm, P3DDT: $50 nm). Films based on composites of the three polymers with PCBM ([6, 6]-phenyl-C61-butyric acid methyl ester) show a distinctive photoluminescence quenching effect. At 77 K two types of light-induced electron spin resonance (LESR) signals were identified, one of polaron (P +Å ) on the polymer chain and one of PCBM ÀÅ radical anion, which detect the photoinduced charge generation and charge transfer in P3AT/PCBM composites.
Advanced Materials, 2007
The discovery of organic electroluminescence (EL) in manufacturable small molecule and p-conjugated polymer thin-film format has led to the commercialization of organic light-emitting diode (OLED) technology and the development of many other novel semiconductor devices. One of the key goals for research in this field is high-performance, fully plastic electronic devices, but before such technology can be realized, organic electrode materials with conductivities and stabilities comparable to standard inorganic materials must be developed. Indium tin oxide (ITO) is the present industry standard transparent inorganic anode material for rigid devices, such as optical displays and solar cells. Attempts have also been made at implementing ITO in an emerging generation of flexible devices, but it is not an ideal choice owing to its inherent brittleness and susceptibility to conductivity changes after bending. When this is considered alongside the ever-increasing cost of indium, it is clear that there is a pressing need to develop organic-based electrode materials for both flexible and rigid substrate devices.
Raman Spectroscopic Characterization of Polyselenophenes and Poly(3,4-ethylenenedioxyselenophene)s
Israel Journal of Chemistry, 2014
Conjugated polymers that can undergo unusual nonoxidative doping were designed. A series of polymers based on donor−acceptor−donor (DAD) moieties 2,1,3-benzoselenadiazole, 2,1,3-benzothiadiazole, 2,1,3-benzoxadiazolebenzo-[2,1,5]oxodiazole, and 2-hexylbenzotriazole as acceptor fragments and 3,4-ethylenedioxyselenophene (EDOS) and 3,4ethylenedioxythiophene (EDOT) as donor fragments was prepared. When the studied polymers were reacted with Lewis acids and bases, notable optical switching and conductivity changes were observed, evidencing the exceptional case of efficient nonoxidative doping/dedoping. Remarkably, in previously reported works, coordination of Lewis acids causes band gap shift but not doping of the conductive polymer, while in the present study, coordination of Lewis acid to highly donating EDOT and EDOS moieties led to polymer doping. The polymers show remarkable stability after numerous switching cycles from neutral to doped states and vice versa and can be switched both electrochemically and chemically. The reactivity of the prepared polymers with Lewis acids and bases of different strengths was studied. Calculation studies of the Lewis acid coordination mode, its effect on polymer energies and band gap, support the unusual doping. The reported doping approach opens up the possibility to control the conjugation, color change, and switching of states of conjugated polymers without oxidation.
Journal of Polymer Science Part A: Polymer Chemistry, 2011
Optical and electrochemical properties of regiosymmetric and soluble alkylenedioxyselenophene-based electrochromic polymers, namely poly(3,3-dibutyl-3,4-dihydro-2H-seleno pheno [3,4-b][1,4]dioxephine) (PProDOS-C 4), poly(3,3-dihexyl-3,4-dihydro-2H-selenopheno[3,4-b][1,4]dioxephine) (PProDOS-C 6), and poly(3,3-didecyl-3,4-dihydro-2H-selenopheno[3,4-b][1,4]dioxephine) (PProDOS-C 10), are highlighted. It is noted that these unique polymers have low bandgaps (1.57-1.65 eV), and they are exceptionally stable under ambient atmospheric conditions. Polymer films retained 82-97% of their electroactivity after 5000 cycles. The percent transmittance of PProDOS-C n (n ¼ 4, 6, 10) films found to be between 55 and 59%. Furthermore, these novel soluble PPro-DOS-C n polymers showed electrochromic behavior: a color change form pure blue to highly transparent state in a low switching time (1.0 s) during oxidation with high coloration efficiencies (328-864 cm 2 C À1) when compared to their thiophene analogues.
Studies of Highly Regioregular Poly (3‐hexylselenophene) for Photovoltaic Applications
Advanced …, 2007
Solar cells based on conjugated polymers are attracting increasing interest due to their potential to enable a renewable energy technology based on simple and low cost manufacture. Devices made from blends of regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) have been widely studied and are consistently reported to produce efficiencies over 3%. Regioregular P3HT is known to be a good hole transporting polymer with relatively long wavelength absorption, producing films with a highly crystalline morphology and good charge mobility (10 -4 cm 2 V -1 s -1 ). According to a model presented by Scharber et al., polymer:PCBM devices could be improved to produce energy conversion efficiencies of up to 11% by replacing P3HT with an electron donating polymer that has better optimised electronic energy levels. In particular, by decreasing the LUMO level of the donor while keeping the HOMO at the same level as P3HT, the reduced band gap would allow a greater light harvesting ability without compromising the open circuit voltage (V oc ).