A polythiophene derivative with dioctyloxyltriphenylamine‐vinylene conjugated side chain: Synthesis,hole mobility,and photovoltaic property

A new polythiophene derivative with dioctyloxyl triphenylamine‐vinylene ( DOTPAV ) conjugated side‐chain, DOTPAV‐PT , was synthesized by the Stille coupling method and characterized by ¹H‐NMR, ¹³C‐NMR, elemental analysis, gel permeation chromatography, thermogravimetric analysis, UV–vis absorption spectroscopy, photoluminescence spectroscopy, and cyclic voltammetry. The polymer DOTPAV‐PT is soluble in common organic solvents and possesses good thermal stability with 5% weight loss temperature of 310°C. The weight‐average molecular weight of DOTPAV‐PT is 8.0 K with a polydispersity index of 1.24. The hole mobility of the polymer determined from space‐charge‐limited current model was 1.25 × 10^?4 cm² V^?1 s^?1. The bulk heterojunction polymer solar cell with the configuration of ITO/PEDOT : PSS/polymer : PCBM (1 : 1)/Ca/Al was fabricated, and the power conversion efficiency of the device was 0.16% under the illumination of AM1.5, 100 mW cm^?2. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and photovoltaic properties of polythiophene derivatives with side chains containing C60 end group

A donor–acceptor double‐cable polythiophene derivative ( PT‐F1 ) with side chain containing C₆₀ end group was synthesized, and characterized by infrared, UV‐vis absorption and photoluminescence (PL) spectroscopy, and electrochemical cyclic voltammetry. Cyclic voltammogram of PT‐F1 shows the oxidation peak of the polymer main chains and the reduction peaks of the C₆₀ end groups, indicating that there is no interaction between the polymer main chains and side chain C₆₀ groups on the ground state. The UV‐vis absorption spectrum of PT‐F1 film is red‐shifted in comparison with that of its chloroform solution. The PL spectrum of the polymer main chain was quenched by the C₆₀ pendant on the side chain. Polymer solar cell with the structure of ITO/PEDOT:PSS/ PT‐F1 /Ca/Al was fabricated. The power conversion efficiency of the device based on PT‐F1 reached 0.274% under the illumination of AM 1.5, 100 mW/cm². © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of a terpolymer containing fluorene,side chain conjugated thiophene and benzothiadiazole and its applications in photovoltaic devices

A terpolymer (POTVTh‐8FO‐DBT) containing fluorene, side chain conjugated thiophene and 4,7‐dithieny‐2,1,3‐benzothiadiazole was synthesized by palladium‐catalyzed Suzuki coupling method. The polymer is soluble in common organic solvents. The thermal, absorption, and electrochemical properties of the polymer were examined. Photovoltaic properties of POTVTh‐8FO‐DBT were studied by fabricating the polymer solar cells (PSCs) based on POTVTh‐8FO‐DBT as donor and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC₆₁BM) as acceptor. With the weight ratio of POTVTh‐8FO‐DBT : PC₆₁BM of 1 : 1 and the active layer thickness of 80 nm, the power conversion efficiency (PCE) of the device reached 0.47% with V_oc = 0.61 V, J_sc = 1.61 mA/cm², and filled factor (FF) = 0.49 under the illumination of AM 1.5, 100 mW/cm². The results indicated that this polymer was promising donor candidates in the application of PSCs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Orientation control of regioregular‐poly(3‐dodecylthiophene) films formed by the friction‐transfer method and the performance of organic photovoltaic devices based on these films

Control of the molecular orientation of regioregular poly(3‐alkylthiophene)s (RR‐P3ATs) improves the performance of field‐effect transistors and organic photovoltaic devices (OPVs). However, most thiophene ring planes of the RR‐P3AT molecules (except RR‐poly(3‐butylthiophene)) in films formed by the conventional spin‐coating method stand on the substrate, that is, edge‐on orientation. Orientation control of RR‐poly(3‐dodecylthiophene) (RR‐P3DDT) molecules in films formed by the friction transfer method is reported and the performance of OPVs based on friction‐transferred RR‐P3DDT films is compared to that of OPVs based on spin‐coated films. The films are investigated by polarized ultraviolet–visible light absorption spectroscopy, Fourier transform infrared spectroscopy, and grazing‐incidence X‐ray diffraction measurement. For friction‐transferred films, the RR‐P3DDT molecular chain is uniaxially aligned parallel to the substrate plane. In addition, the thiophene ring planes of the RR‐P3DDT molecules are also oriented parallel to the substrate plane, that is, face‐on orientation. The power conversion efficiency (PCE) and fill factor of the RR‐P3DDT/C₆₀ bilayer OPVs based on the friction‐transferred RR‐P3DDT films are higher than those of devices based on spin‐coated films. The PCE and photocurrent of the device based on the friction‐transferred film are larger under irradiation with polarized light parallel to the RR‐P3DDT molecular chain direction than with polarized light orthogonal to the chain direction. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40136.     

Synthesis of a soluble conjugated copolymer based on dialkyl-substituted dithienothiophene and its application in photovoltaic cells

A soluble conjugated alternating 3,5-didecanyldithieno[3,2-b:2′,3′-d]thiophene-thiophene copolymer was synthesized by palladium(0)-catalyzed Stille coupling reaction. The thermal, absorption, emission, electrochemical, and photovoltaic properties of the polymer were examined. A weight-average molecular weight around 6.2 × 10⁴ and a polydispersity index of 1.8 was estimated for the polymer using gel permeation chromatography. The polymer exhibits good thermal stability with decomposition temperature of 340 °C and glass-transition temperature of 136 °C. The polymer shows strong absorption peaked at 505 nm in diluted solution and 518 nm in thin film with an optical band gap 2.0 eV. The polymer exhibits intense emission located at 550 nm in solution and 603 nm in film. The HOMO and LUMO energies of the polymer were estimated to be −5.4 and −3.4 eV, respectively, by cyclic voltammetry. Polymer solar cells were fabricated based on the blend of the polymer and methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM). The power conversion efficiency of 0.7% was achieved under AM 1.5, 100 mW/cm² using polymer:PCBM (1:4, w/w) as active layer.     

Synthesis,characterization, and photophysical properties of novel poly(p‐phenylene vinylene) derivatives with conjugated thiophene as side chains

Two novel poly(p‐phenylene vinylene) (PPV) derivatives with conjugated thiophene side chains, P1 and P2, were synthesized by Wittig‐Horner reaction. The resulting polymers were characterized by ¹H‐NMR, FTIR, GPC, DSC, TGA, UV–Vis absorption spectroscopy and cyclic voltammetry (CV). The polymers exhibited good thermal stability and film‐forming ability. The absorption spectra of P1 and P2 showed broader absorption band from 300 to 580 nm compared with poly[(p‐phenylene vinylene)‐alt‐(2‐methoxy‐5‐octyloxy‐p‐phenylene vinylene)] (P3) without conjugated thiophene side chains. Cyclic voltammograms displayed that the bandgap was reduced effectively by attaching conjugated thiophene side chains. This kind of polymer appears to be interesting candidates for solar‐cell applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterizations of poly(4‐alkylthiazole vinylene)

Two poly(thiazole vinylene) derivatives, poly(4‐hexylthiazole vinylene) (P4HTzV) and poly(4‐nonylthiazole vinylene) (P4NTzV), were synthesized by Pd‐catalyzed Stille coupling method. The polymers are soluble in common organic solvents such as o‐dichlorobenzene and chloroform, and possess good thermal stability. P4HTzV and P4NTzV films exhibit broad absorption bands at 400–720 nm with an optical bandgap of 1.77 eV and 1.74 eV, respectively. The HOMO (the highest occupied molecular orbital) energy levels of P4HTzV and P4NTzV are ?5.11 and ?5.12 eV, respectively, measured by cyclic voltammetry. Preliminary results of the polymer solar cells based on P4HTzV : PC₆₁BM ([6,6]‐phenyl‐C‐61‐butyric acid methyl ester) (1 : 1, w/w) show a power conversion efficiency of 0.21% with an open‐circuit voltage of 0.55 V and a short circuit current density of 1.11 mA cm^?2, under the illumination of AM1.5G, 100 mW cm^?2. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Donor copolymer with benzo[1,2‐b:4,5‐b′]dithiophene and quinoxaline derivative segments for photovoltaic applications

A donor copolymer Poly{2,6‐4,8‐bis(2‐ethylhexyl)benzo[1,2‐b:3,4‐b′]dithiophene‐5,8‐2,3‐bis(5‐octylthiophen‐2‐yl)quinoxaline} (PBDTThQx) with benzo[1,2‐b:4,5‐b′]dithiophene and quinoxaline derivatives was synthesized and characterized with NMR, ultraviolet–visible spectroscopy, thermogravimetric analyses, and cyclic voltammetry. Photovoltaic devices with the configuration indium tin oxide–poly(3,4‐ethylenedioxythiophene)–poly(styrene sulfonate)–PBDTThQx–[6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM)–LiF–Al were fabricated, in which PBDTThQx performed as the electron donor and PC₆₁BM was the electron acceptor in the active layer. The device presented reasonable photovoltaic properties when the weight ratio of PBDTThQx:PC₆₁BM reached 1:3. The open‐circuit voltage, fill factor, and power conversion efficiency were gauged to be 0.75 V, 0.59, and 0.74%, respectively. The experimental data implied that PBDTThQx would be a promising donor candidate in the application of polymer solar cells. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40279.     

Effect of the regioregularity of poly(3‐hexylthiophene) on the performances of organic photovoltaic devices

BACKGROUND: The highest efficiencies of bulk‐heterojunction solar cells from poly(3‐hexylthiophene) (P3HT) and [6,6]‐phenyl C₆₁‐butyric acid methyl ester (PCBM) reported so far are close to 6%. Phenomena occurring during the photovoltaic process, such as the creation, diffusion and separation of excitons, as well as charge carrier transport, are governed by the active layer morphology. The latter phenomenon, which depends on the self‐organization of P3HT, can be influenced by its degree of regioregularity. The aim of this work is to clarify the relationship between the regioregularity of P3HT, the composition of P3HT/PCBM blends and the performances of photovoltaic devices. RESULTS: Two types of P3HTs with different degrees of regioregularity have been synthesized and used as active layers with PCBM in photovoltaic cells. The higher performances in photovoltaic devices are obtained for high‐regioregular P3HT and can be explained considering the self‐organizing properties of high‐regioregular P3HT, leading to higher sunlight absorption and higher hole mobilities. In addition, this report demonstrates the importance of the ratio of P3HT versus PCBM in correlation with the regioregularity of P3HT on the optical properties, charge transport and characteristics of photovoltaic cells. CONCLUSION: We have investigated the dependence of the photovoltaic properties of P3HT/PCBM blend‐based photovoltaic devices on the degree of regioregularity of P3HT. We find that the best performance is exhibited by devices based on highly regioregular P3HT. Also, the best performances are not obtained for the same P3HT:PCBM weight ratios for high‐regioregular P3HT (1:0.8) and low‐regioregular P3HT (1:3). Copyright © 2007 Society of Chemical Industry     

Theoretical evaluation of chemical substitutions along the main chain of poly(3‐hexylthienylene‐vinylene) for solar cell applications

In order to improve the efficiency of bulk‐heterojunction organic solar cells, one can try to optimize the active layer through the use of new materials that provide improvements in the parameters that influence the final efficiency of a device. The use of chemical substitutions in organic materials already used in these devices seems to be an efficient methodology to obtain new materials with better intrinsic properties. Based on this idea, in this work is investigated theoretically, by methods of electronic structure calculation, a set of 143 poly(3‐hexylthienylene‐vinylene) (P3HTV) derivatives for application in active layers of organic solar cells as electron donor materials; the chemical modifications were performed on the thiophene ring and the vinyl segment of P3HTV. The results show that it is possible to obtain several new derivatives with better optical and electronic properties than those of P3HTV. The derivative substituted with trifluoromethyl on the vinyl segment is one of the most promising for use in active layers, when combined with phenyl‐C61‐butyric‐acid‐methyl‐ester as electron acceptor material. An equation to predict the electronic properties of P3HTV derivatives when using more than one chemical substitution is also proposed, which is corroborated by the theoretical calculations. © 2017 Society of Chemical Industry     

Synthesis,characterization, and electro‐optical properties of a soluble conjugated polymer containing an oxadiazole unit in the main chain

A novel copolymer, poly{[2,5‐diphenylene‐1,3,4‐oxadiazole‐vinylene]‐alt‐[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene]}(MEH‐OPPV) containing a high‐electron‐affinity unit of aromatic oxadiazole in the main chain is synthesized through the Wittig condensation reaction. The obtained copolymer is easily soluble in conventional organic solvents. The structure of the copolymer was characterized by Fourier transform infrared, ¹H nuclear magnetic resonance, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and ultraviolet‐visible and photoluminescence spectroscopy. The TGA result indicates that the copolymer has very high thermal stability (stable up to 310°C in nitrogen), while DSC investigation demonstrates that the glass transition temperature (T_g) is 143°C, which might be a merit for the long‐life operation of light‐emitting devices. The absorption spectrum of film sample of the copolymer reveals two peaks at 310 and 370 nm, respectively, and the edge absorption corresponds to a band gap of 2.46 eV. A single‐layer light‐emitting diode device ITO/MEH‐OPPV/Al is successfully fabricated. The device emits visible yellowish‐green light above the bias voltage of 4.0 V under ambient condition. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2618–2623, 2003     

Synthesis of conjugated polymers with broad absorption bands and photovoltaic properties as bulk heterojuction solar cells

Two new broad absorbing alternating copolymers, poly[1-(2,6-diisopropylphenyl)-2,5-bis(2-thienyl)pyrrole-alt-4,7-bis(3-octyl-2-thienyl)benzothiadiazole] (PTPTTBT-P1) and poly[1-(p-octylphenyl)-2,5-bis(2-thienyl)pyrrole-alt-4,7-bis(3-octyl-2-thienyl)benzothiadiazole] (PTPTTBT-P2), were prepared via Suzuki polycondensation with high yields. The two polymers were found to show characteristic absorption in the visible region of the solar spectrum. Interestingly the absorption of PTPTTBT-P1 was found to cover the visible region from 350 to 650 nm with the broad and flat absorption maximum from 440 to 510 nm in film and the absorption of PTPTTBT-P2 was found to cover the visible region from 350 to 950 nm with the relatively distinct absorption maxima at 425 and 522 nm and very weak absorption maximum at 832 nm in film. The electrochemical band gaps of the polymers were calculated to be 1.88 eV and 1.87 eV, respectively, while the optical band gaps of the polymers were calculated to be 1.94 eV and 1.87 eV, respectively. The photovoltaic properties of polymers were investigated with bulk heterojunction (BHJ) solar cells fabricated in ITO/PEDOT:PSS/polymer:PC₇₀BM(1:5 wt%)/TiOx/Al configurations. The maximum power conversion efficiency (PCE) of the solar cell composed of PTPTTBT-P1:PC₇₀BM as an active layer was 1.57% with current density (J_sc) of 8.17 mA/cm², open circuit voltage (V_oc) of 0.52 V and fill factor (FF) of 36%.     

Synthesis of oxadiazole‐based polymers containing a carbazole–vinylene or fluorene–vinylene group and their hole‐injection/transport behavior in light‐emitting diodes

A series of conjugated (poly{N‐(2‐ethylhexyl)‐3,6‐carbazole–vinylene‐alt‐[(2,5‐bisphenyl)‐1,3,4‐oxadiazole]}) and nonconjugated (poly{N‐(2‐ethylhexyl)‐3,6‐carbazole–vinylene‐alt‐[(2,5‐bisphenol)‐1,3,4‐oxadiazole]}) and poly{9,9‐dihexyl‐2,7‐fluorene–vinylene‐alt‐[(2,5‐bisphenol)‐1,3,4‐oxadiazole]}) polymers containing oxadiazole and carbazole or fluorene moieties in the polymer backbone were synthesized with a multiple‐step procedure. The properties of the polymers, including the photophysical and electrochemical characteristics, could be fine‐tuned by adjustment of the components or structures in the polymer chains. The polymers were used to examine the hole‐injection/transport behavior as hole‐injection/hole‐transport layers in double‐layer indium tin oxide (ITO)/polymer/aluminum tris(8‐hydroxyquinoline)/LiF/Al devices by the determination of their energy levels. The effects of the polymers in these devices on the charge‐transport behavior were compared with a control device fabricated with poly(ethylenedioxythiophene) (PEDOT)–poly(styrene sulfonate) (PSS). Devices containing the synthesized polymers showed comparable adhesion to the ITO anode and good hole‐injection/transport performance. In addition, they exhibited higher electroluminescence over an identical range of current densities than the control device. This was attributed to the prevention of radiative exciton quenching caused by the PEDOT–PSS interfaces and the improvement of electron/exciton blocking due to the higher electron affinity of the synthesized polymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Direct (hetero)arylation polymerization for the synthesis of donor–acceptor conjugated polymers based on N‐benzoyldithieno [3,2‐b:2′,3′‐d]pyrrole and diketopyrrolopyrrole toward organic photovoltaic cell application

In this research, new donor–acceptor (D‐A) photovoltaic polymers were synthesized from dithieno[3,2‐b:2′,3′‐d]pyrrole electron donor derivatives, including N‐benzoyldithieno[3,2‐b:2′,3′‐d]pyrrole and N‐(4‐hexylbenzoyl)dithieno[3,2‐b:2′,3′‐d]pyrrole, in combination with the electron deficient unit 2,5‐bis(2‐ethylhexyl)‐3,6‐di(thiophen‐2‐yl)‐2,5‐dihydropyrrolo[3,4‐c]pyrrole‐1,4‐dione via direct (hetero)arylation polymerization. The D‐A conjugated polymers obtained were characterized via ¹H NMR, gel permeation chromatography, Fourier transform infrared spectroscopy, DSC, XRD, photoluminescence and UV–visible methods. In addition, these D‐A polymers were used as activated layers in bilayer and bulk heterojunction structures for the fabrication of organic photovoltaic cells. © 2019 Society of Chemical Industry     

Review of electronic and optical properties of semiconducting π‐conjugated polymers: applications in optoelectronics

A general overview of the optoelectronic properties of π‐conjugated polymers is presented. Two types of polymer are discerned: interchangeable structures of the same energy (degenerate), such as polyacetylene; and non‐degenerate polymers, such as poly(para‐phenylene). The band structures of degenerate and non‐degenerate polymers are related to their conductivities in doped and non‐doped states. In both cases, disorder and impurities play an important role in conductivity. Polarons, bipolarons and excitons are detailed with respect to doping and charge transfers. Given the fibrillic nature of these materials, the variable range hopping (VRH) law for semiconducting polymers is modified to account for metallic behaviours. Optoelectronic properties—electroluminescence and photovoltaic activity—are explained in terms of HOMO and LUMO bands, polaron‐exciton and charge movement over one or more molecules. The properties of H‐ or J‐type aggregates and their effects on transitions are related to target applications. Device structures of polymer light‐emitting diodes are explicitly linked to optimising polaron recombinations and overall quantum efficiencies. The particularly promising use of π‐conjugated polymers in photovoltaic devices is discussed. Copyright © 2004 Society of Chemical Industry     

Fluorene‐based copolymers with donor–acceptor units on the side chain and main chain: Synthesis and application in polymer solar cells

Two narrow band gap fluorene‐based copolymers with donor–acceptor (D–A) structure on the polymer side chain and/or main chain are synthesized by Pd‐catalyzed Stille coupling reactions. The two copolymers have excellent thermal stability. The effects of D–A structure on the main and side chains on the absorption and electrochemical properties are studied. The copolymer PF‐BTh‐DBT with D–A structure both on the main and side chains has broader and stronger absorption and narrower band gap than the copolymer PF‐BTh with only a pendent D–A structure. The power conversion efficiency of the assembled solar cell using PF‐BTh‐DBT as donor and PC₇₁BM as acceptor is 1.6% with open‐circuit voltage (V_oc) 0.84 V under simulated AM 1.5 G solar irradiation (100 mW/cm²). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3276–3281, 2013     

Synthesis and electroluminescent properties of a novel copolymer with short alternating conjugated and non‐conjugated blocks

A new electroluminescent copolymer [poly(1,5‐di(3,5‐dimethyloxystyrylene)naphthalene‐block‐tri(ethylene oxide)) (DSN–TEO)], containing alternating rigid, conjugated light‐emitting units and flexible tri(ethylene oxide) ionic conductive units, was synthesized via the Wittig reaction. The polymer has fairly good solubility in chloroform, tetrahydrofuran, toluene, etc, and excellent film‐forming ability. The decomposition temperature and the glass transition temperature were 409 °C and 42.2 °C, respectively. A light‐emitting diode (LED) device with configuration ITO/PEDOT–PSS/DSN–TEO/Ca(Al) and light‐emitting electrochemical cell (LEC) device with ITO/DSN–TEO + PEO (LiTf)/Al were prepared, and the photoluminescence and electroluminescence (EL) properties were investigated. Efficient blue‐green light emission (EL maximum emissive wavelength at 508 nm) was found with onset voltage at 6 V. The maximum light efficiency was 0.107 cd A^?1 at 20 V for LED, and the onset voltage 2.5 V and the maximum light efficiency was 4.2 cd A^?1 at 2.8 V for LEC, respectively. The response time of the LEC was less than 5 s. The EL efficiency of LEC device was improved by 44 as compared with the relative LED device. © 2003 Society of Chemical Industry     

Synthesis,characterization, electrochemistry and optical properties of a novel phenanthrenequinone‐ alt‐dialkylfluorene conjugated copolymer

This paper describes the synthesis, characterization and electro‐optical properties of a 9,10‐phenanthrenequinone (PQ)‐containing alternating conjugated copolymer: poly[(9,10‐phenanthrenequinone‐2,7‐diyl)‐alt‐(9,9‐di‐n‐hexylfluorene‐2,7‐diyl)] (PPQF). The copolymer has good solubility in common organic solvents such as CH₂Cl₂, CHCl₃ and tetrahydrofuran. The polymer structure was determined using ¹H NMR, Fourier transform infrared spectroscopy, gel permeation chromatography and elemental analysis. The polymer possesses a low‐energy n → π* electronic state caused by the C?O groups of the PQ repeating units, and exhibits interesting and improved electrochemical reduction activity as compared to poly(9,9‐di‐n‐hexylfluorene‐2,7‐diyl) and molecular PQ. PPQF has no fluorescence in solution but shows interesting transitions from no fluorescence to strong fluorescence after it undergoes electrochemical reduction. The polymer PPQF may find use as a starting material for a range of applications and can also be used to prepare other polymers due to the presence of the PQ repeating units. Copyright © 2007 Society of Chemical Industry     

Synthesis and characterization of light‐absorbing cyclopentadithiophene‐based donor–acceptor copolymers

Cyclopentadithiophene and benzothiadiazole based donor–acceptor polymers are fast emerging as the most promising class of materials for organic solar cells. Here we report on a series of Cyclopentadithiophene and benzothiadiazole based conjugated polymers, namely poly[4,7‐bis(4,4‐dioctyl‐4H‐cyclopenta[2,1‐b;3,4‐b′]dithiophene‐2‐yl)benzo[1,2,5]thiadiazole] (P1), poly[4,7‐bis(4,4‐dioctyl‐4H‐cyclopenta[2,1‐b;3,4‐b′]dithiophene‐2‐yl)benzo[1,2,5]thiadiazole‐alt‐9‐(heptadecan‐9‐yl)‐2,7‐bis(4,4,5,5‐tetramethyl)‐1,3,2‐dioxaborolan‐2‐yl)‐9H‐carbazole] (P2) and poly[4,7‐bis(4,4‐dioctyl‐4H‐cyclopenta[2,1‐b;3,4‐b′]dithiophene‐2‐yl)benzo[1,2,5]thiadiazole‐alt‐5,11‐bis(2‐hexyldecyl)‐3,9‐bis(4,4,5,5‐tetramethyl)‐1,3,2‐dioxaborolan‐2‐yl)‐5,11‐dihydroindolo[3,2‐b]carbazole] (P3), with alternating donor and acceptor units and discuss their photophysical and electrochemical properties. Stille coupling of 2‐tributylstannyl‐4,4‐dioctylcyclopenta[2,1‐b:3,4‐b′]dithiophene with 4,7‐dibromobenzo[1,2,5]thiadiazole generated the alternating donor–acceptor monomer 4,7‐bis(4,4‐dioctyl‐4H‐cyclopenta[2,1‐b;3,4‐b′]dithiophene‐2‐yl)benzo[1,2,5]thiadiazole (CPDT‐BT‐CPDT). Homopolymer P1 of CPDT‐BT‐CPDT was synthesized by oxidative polymerization using FeCl₃. Copolymers P2 and P3 were synthesized by palladium‐catalysed Suzuki polycondensation. The synthesized polymers showed good solubility in common organic solvents, and UV‐visible measurements showed that the absorption maxima of the polymers lie in the range 624 to 670 nm. The energy gaps of these polymers were found to lie in the range 1.29 to 1.50 eV. Gel permeation chromatography measurements against polystyrene standards showed the number‐average molecular weight to be in the range (2.2–6.0) × 10⁴ g mol^?1. Thermogravimetric analysis showed the polymers to possess high thermal stability. A preliminary study of photodiode devices prepared using polymers P1, P2 and P3 when blended with the PC₇₁BM electron acceptor found that P2 is the optimum chemical structure for pursuing further device optimization.© 2015 Society of Chemical Industry     

Synthesis and characterization of sulfonated fluorinated block copolymer membranes with different esterified initiators for DMFC applications

This investigation studied the synthesis of ionic membranes composed of a sulfonated poly(styrene‐isobutylene‐styrene) with novel fluoroblock copolymers. These fluoroblock copolymers were synthesized using three different initiators by Atom Transfer Radical Polymerization (ATRP); two fluoroinitiators were obtained from the esterification of 2‐(perfluoroalkyl) ethanol or octafluoro 4‐4′‐biphenol. The third initiator evaluated was 1‐bromoethyl benzene. The resulting block copolymers were characterized using several techniques: Gel Permeation Chromatography, Nuclear Magnetic Resonance, Fourier Transform Infrared Spectroscopy, Ultraviolet Spectroscopy, Thermogravimetric Analysis, and Differential Scanning Calorimetry. Transport properties (e.g., proton conductivity and methanol permeability) were measured to evaluate their performance for direct methanol fuel cell (DMFC). The choice of ATRP initiator was found to have a profound impact on the thermal stability of the different homopolymers and block copolymers studied. In addition, the chemical nature and symmetry of the initiators can lead to different chemical and electronic transitions, which influence the performance of these ionic membranes in applications such as proton exchange membranes for DMFC applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42046.