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In situattenuated total reflection Fourier transform infrared (ATR-FTIR) spectroelectrochemistry during oxidation (p-doping) and reduction (n-doping) of three phenyl-substituted polythiophenes, namely POPT, PEOPT and POMeOPT is presented. All the three phenyl substituted polythiophenes show both n- and p-doping. The infrared active vibration (IRAV) patterns obtained during electrochemical oxidation (p-doping) and reduction (n-doping) are compared. HOMO and LUMO energy levels are estimated from cyclic voltammetric experiments and from IRAV patterns during oxidation and reduction. A comparison shows that the standard graphical procedure to determine the onset of oxidation and reduction peaks in the cyclic voltammogram can be improved using in situspectroscopy. [ABSTRACT FROM AUTHOR]

Conjugated Polymers with a HOMO-LUMO transition <2 eV, i.e. a low bandgap, respectively, have interesting and desired properties for some thin film optoelectronic devices like light emitting diodes and solar cells. In this contribution we present the implementation of the novel copolymer PTPTB, consisting of alternating electron-rich N -dodecyl-2,5-bis(2′thienyl)pyrrole (TPT and electron-deficient 2,1,3-benzothiadiazole (B) units, in light emitting diodes (LEDs ) and photovoltaic devices. The LEDs show emission in the near infrared region, peaking at 800 nm. The electroluminescence yield can be significantly enhanced by blending with the wide bandgap polymer poly (para-phenylene-vinylene) derivative MDMO-PPV. Bulk heterojunction devices of PTPTB blended with the C 60 derivative PCBM shows AM 1.5 efficiencies around 1%. The low bandgap of PTPTB allows collecting photons up to 750 nm. [ABSTRACT FROM PUBLISHER]

Abstract: Solution-processed bilayer heterojunction hybrid solar cells have been fabricated using size-quantized PbS nanoparticles and poly (3-hexylthiophene) (P3HT). PbS was used as an electron-transporting layer whereas P3HT was used for hole transport. A photovoltaic device consisting of PbS and P3HT exhibited 3% incident photon to current efficiencies (IPCE) under 550-nm monochromatic irradiation. [Copyright &y& Elsevier]

Abstract: Photophysical studies and photovoltaic devices on a low bandgap, high-charge carrier mobility poly(thienylene vinylene) (PTV), prepared from a soluble precursor polymer synthesised via the “dithiocarbamate route”, are reported. In composites with an electron acceptor ([6,6]-phenyl C61-butyric acid methyl ester (PCBM), a soluble fullerene derivative), photoinduced absorption characteristic for charged excitations together with photoluminescence quenching are observed indicating photoinduced electron transfer. The “bulk heterojunction” photovoltaic devices using PTV and PCBM composites show short-circuit currents up to 4mA/cm2 under AM 1.5 white-light illumination. The photocurrent spectrum of the photovoltaic device shows an onset about 1.65eV (750nm), which corresponds to the absorption spectrum of the polymer. [Copyright &y& Elsevier]

Abstract: A series of novel polyimides and copolyimides were obtained by combining 2,7-dimethylacridine-3,6-diamine with one of three aromatic dianhydrides: 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-(4,4′-isopropylidene-diphenoxy)bis(phthalic anhydride) and 4,4′-tetraphthaloyl-bis(1,8-naphthalene dicarboxylic)dianhydride. The resultant polymers showed glass transition temperatures (T g) in the range 209–331 °C and decomposition temperature (T d) in the range of 370–475 °C. The optical properties, absorption and photoluminescence (PL) of the obtained polymers were investigated in solution and in the solid state as blends with inert poly(methyl methacrylate). The polymers dissolved in NMP emitted blue or green light with the maximum emission wavelength in the range of 438–512 nm, while emitting blue light in the solid state. The electrochemical behavior of the polyimides was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). They exhibited electrochemical band gap in the range of 1.36–2.94 eV. Spectroelectrochemical experiments showed reversible switching between neutral violet and blue, blue-green, green, yellow and red colors corresponding to two reduction anion and dianion states depending on polymer backbone structure. [Copyright &y& Elsevier]

Abstract: The rhenium complex fac-(5,5′-bisphenylethynyl-2,2′-bipyridyl)Re(CO)3Cl was used as a novel catalyst for the electro- and photochemical reduction of CO2 to CO in homogeneous solution. The results were compared to (2,2′-bipyridyl)Re(CO)3Cl as a benchmark compound. Cyclic voltammetric studies as well as bulk controlled potential electrolysis experiments were performed using a CO2 saturated solution in acetonitrile. (5,5′-bisphenylethynyl-2,2′-bipyridyl)Re(CO)3Cl showed a 6.5-fold increase in current density under CO2 at −1750 mV versus normal hydrogen electrode (NHE) as compared to the operation without CO2. Quantitative analysis by gas chromatography (GC) and infrared spectroscopy showed a Faradaic efficiency of around 45% for the formation of CO. [Copyright &y& Elsevier]

Abstract: By electrochemically p-doping pentacene in the vicinity of the source-drain electrodes in organic field effect transistors the injection barrier for holes is decreased. The focus of this work is put on the influence of the p-doping process on the transistor performance. Cyclic voltammetry performed on a pentacene based transistor exhibits a reversible p-doping response. This doped state is evoked at the transistor injection electrodes. An improvement is observed when comparing transistor characteristics before and after the doping process apparent by an improved transistor on-current. This effect is reflected in the analysis of the contact resistances of the devices. [Copyright &y& Elsevier]

Abstract: Here the device performance is shown to be directly related to the measured electronic level alignment at the dielectric interface in C60 organic field effect transistors (OFETs). We compare C60 on two dielectrics: Al2O3 and a divinyltetramethyldisiloxane-bis(benzocyclobutene) (BCB)–Al2O3 bilayer. The improved transistor performance and the lowering of the threshold voltage by 0.8V due to the BCB interlayer are reflected in the ultra-violet photoemission data. These show a 0.8eV difference in the work function and a concomitant shift in the C60 valence band. By following the work function the improvement is shown to be due to the dipole at the organic BCB–C60 interface. [Copyright &y& Elsevier]

Abstract: Considerable interest exists in the development of novel n-type conjugated polymers, since many currently available polymer systems have insufficient electron mobility and/or electron affinity. In this work, a universal synthesis route is presented towards a new class of n-type conjugated polymers, i.e. poly(p-fluoranthene vinylene) (PFV) and its derivatives. This route is illustrated with three examples, i.e. unsubstituted PFV and functionalized hexyl-PFV and dodecyl-PFV. All polymers have been synthesized via the dithiocarbamate precursor route. Solubility was introduced by incorporation of alkyl side chains, which leads to a significantly enhanced purity and processability as compared to unsubstituted PFV. Under the applied electrochemical conditions PFV-type polymers demonstrate typical n-type behavior. Additional CELIV mobility measurements on dodecyl-PFV reveal an excellent electron mobility, μe =1.4×10−4 cm2/Vs. Hence, poly(p-fluoranthene vinylene) and its derivatives are promising n-type materials for organic optoelectronic applications. [Copyright &y& Elsevier]

Abstract: Poly-(2,5-Thienylene Vinylene) (PTV) derivatives have been synthesised via the “dithiocarbamate precursor route” in good yield and satisfactory molecular weight. Structural characterisations of the conjugated PTV polymers reveal an optical band gap around 1.8 eV. Organic field effect transistors and organic based photovoltaic devices were made with the plain PTV, via a precursor approach. More specifically, solar cells were produced using a blend of the precursor PTV polymer and PCBM (1-(3-methoxycarbonyl) propyl-1-phenyl [6,6] C61) at various ratios, converted in situ in thin film. A promising power efficiency of 0.76% was achieved. [Copyright &y& Elsevier]

Abstract: We report the photophysical behavior and photovoltaic performance of a poly(3,4-propylenedioxythiophene) (PProDOT) derivative, namely poly-[3,3-dihexyl-3,4-dihydro-2H-thieno(3,4-b)(1,4)dioxepine] (PProDOT(Hx)2), as an electron donor in bulk heterojunction solar cells blended with the acceptor 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene (PCBM). Devices composed of a 1:4 (w:w) ratio of PProDOT(Hx)2/PCBM and spin coated from chlorobenzene were characterized by measuring current–voltage characteristics under simulated Air Mass 1.5 (AM1.5) conditions as well as the spectrally resolved photocurrent (IPCE). The influence of different preparation parameters like various blend ratios, spin coating from different solvents, and changing the metal contacts was studied. It was found that the photoluminescence of the polymer is quenched by a factor greater than 100 using blends consisting of PProDOT(Hx)2 and PCBM (3:2, w:w). Additionally, the photoactive blends were characterized by photoinduced absorption spectroscopy and the results suggest that charge transfer is occurring from PProDOT(Hx)2 to PCBM. Results from atomic force microscopy reveal that a bicontinuous network, with domain sizes on the order of 100–200nm, results when a 1:4 blend of PProDOT(Hx)2/PCBM is spin coated from chlorobenzene. [Copyright &y& Elsevier]

When studying electrochemical oxygen reduction reactions in homogeneous media, special attention must be given to the significant background activity present with conventional electrode materials. The intrinsic electrocatalytic activity of different materials can be investigated using complementary methods, such as the rotating ring-disc electrode (RRDE) technique and chronoamperometric electrolysis with product quantification. This report presents a detailed investigation of the electrocatalytic ability of hydroxy anthraquinone derivatives and riboflavin towards hydrogen peroxide (H 2 O 2 ) production via a novel RRDE subtraction method together with chronoamperometric electrolysis. Qualitative trends linking the two methods were obtained, such as a higher excess current correlating with both higher productivity and selectivity. As such, a valuable tool is provided to increase the understanding of the electrocatalytic ability of homogeneous solutions toward improving the oxygen reduction reaction., Competing Interests: The authors have declared, they have no conflict of interest regarding this content., (This journal is © The Royal Society of Chemistry.)

Electrochemical capture of carbon dioxide (CO 2 ) using organic quinones is a promising and intensively studied alternative to the industrially established scrubbing processes. While recent studies focused only on the influence of substituents having a simple mesomeric or nucleophilicity effect, we have systematically selected six anthraquinone (AQ) derivatives (X-AQ) with amino and hydroxy substituents in order to thoroughly study the influence thereof on the properties of electrochemical CO 2 capture. Experimental data from cyclic voltammetry (CV) and UV-Vis spectroelectrochemistry of solutions in acetonitrile were analyzed and compared with innovative density functional tight binding computational results. Our experimental and theoretical results provide a coherent explanation of the influence of CO 2 on the CV data in terms of weak and strong binding nomenclature of the dianions. In addition to this terminology, we have identified the dihydroxy substituted AQ as a new class of molecules forming rather unstable [X-AQ-(CO 2 ) n ] 2- adducts. In contrast to the commonly used dianion consideration, the results presented herein reveal opposite trends in stability for the X-AQ-CO 2 •- radical species for the first time. To the best of our knowledge, this study presents theoretically calculated UV-Vis spectra for the various CO 2 -AQ reduction products for the first time, enabling a detailed decomposition of the spectroelectrochemical data. Thus, this work provides an extension of the existing classification with proof of the existence of X-AQ-CO 2 species, which will be the basis of future studies focusing on improved materials for electrochemical CO 2 capture., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

In this report, we present results on the electrocatalytic activity of conducting polymers [polyaniline (PANI) and polypyrrole (PPy)] toward the electrochemical oxygen reduction reaction (ORR) to hydrogen peroxide (H 2 O 2 ). The electropolymerization of the polymers and electrolysis conditions were optimized for H 2 O 2 production. On flat glassy carbon (GC) electrodes, the faradaic efficiency (FE) for H 2 O 2 production was significantly improved by the polymers. Rotating disc electrode (RDE) studies revealed that this is mainly a result of blocking further H 2 O 2 to the water reduction pathway by the polymers. PPy on carbon paper (CP) significantly increased the molar production of H 2 O 2 by over 250% at an average FE of above 95% compared to bare CP with a FE of 25%. Thus, the polymers are acting as catalysts on the electrode for the ORR, although their catalytic mechanisms differ from other electrocatalysts., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)

Developing efficient methods for capture and controlled release of carbon dioxide is crucial to any carbon capture and utilization technology. Herein we present an approach using an organic semiconductor electrode to electrochemically capture dissolved CO 2 in aqueous electrolytes. The process relies on electrochemical reduction of a thin film of a naphthalene bisimide derivative, 2,7-bis(4-(2-(2-ethylhexyl)thiazol-4-yl)phenyl)benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone (NBIT). This molecule is specifically tailored to afford one-electron reversible and one-electron quasi-reversible reduction in aqueous conditions while not dissolving or degrading. The reduced NBIT reacts with CO 2 to form a stable semicarbonate salt, which can be subsequently oxidized electrochemically to release CO 2 . The semicarbonate structure is confirmed by in situ IR spectroelectrochemistry. This process of capturing and releasing carbon dioxide can be realized in an oxygen-free environment under ambient pressure and temperature, with uptake efficiency for CO 2 capture of ∼2.3 mmol g -1 . This is on par with the best solution-phase amine chemical capture technologies available today.

[Structure: see text] A novel covalently linked bis([60]fullerene)-phthalocyanine triad is reported, exhibiting long-lived photoinduced charge separation both in solution and in the solid state. The first demonstration of a working solar cell using triad 1 as the active material is also presented.

New donor-acceptor materials based on a polynorbornene framework to which both phthalocyanine and C60 electroactive pendant units are randomly attached have been prepared in good yield by ring-opening-metathesis polymerization (ROMP) in the presence of a Grubbs catalyst. A structurally related phthalocyanine homopolymer was also synthesized for comparison. A remarkable fluorescence quenching was observed in the homopolymer and accounts for PcPc interactions along the polymeric framework. As expected, the fluorescence quenching increases in the case of the polynorbornenes containing both Pc and C60 units owing to photoinduced electron transfer, which was further confirmed by transient absorption spectroscopy. Finally, preliminary solar cell devices made of one of the copolymers were constructed.

Poly(3,4-ethylenedithiathiophene) (PEDTT) is a polythiophene-like conjugated polymer in which each thiophene ring is functionalized with an ethylenedithia bridge. As such, PEDTT is the sulfur analogue of the well-known poly(3,4-ethylenedioxythiophene) (PEDOT). Substituent effects, namely the presence of sulfur atoms in PEDTT replacing the oxygen atoms of PEDOT, do not provide a simple explanation for the different electronic properties of the two polymers in the neutral state. This paper reports the spectroscopic properties of PEDTT, studied by in situ techniques such as IR-, Vis-, and electron spin resonance (ESR) spectroelectrochemistry. The differences observed upon electrochemical oxidation of PEDTT and PEDOT (e.g., the different infrared active vibrational band patterns in IR spectroelectrochemistry as well as the different nature of the charged states) are even more marked than those observed in the neutral state. These results, with AM1 calculations, indicate conformational effects as a possible explanation for the different electronic and spectroscopic properties of PEDTT and PEDOT.