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The unprecedented increase in power conversion efficiency (PCE) of low‐cost organo‐inorganic halide perovskite solar cells (OIHPSCs) toward its Shockley‐Queisser limit intriguingly has prompted researchers to investigate the disadvantages of these devices. The issue of operational stability is the main hurdle challenging the way forward for commercialization. To address this, various engineering processes like composition, additives, anti‐solvents, bulk and interface passivation, and deposition techniques have been widely applied to manage both extrinsic and intrinsic factors that induce degradation of the OIHPSCs. In this work, we employed interface passivation, which is an efficient approach to reduce nonradiative recombination. An ultrathin layer of electron donor diketopyrrolopyrrole‐oligothiophene copolymer (DPP860) was applied as an interface passivator between the photoactive layer and [6,6]‐phenyl C61 butyric acid methyl ester (PCBM). The role of the interface passivation on optoelectronic properties of the OIHPSCs was assessed using current density versus voltage (J‐V) characteristics, photoluminescence spectroscopy and time‐resolved photoluminescence spectroscopy. The findings show devices treated with DPP860 exhibit enhanced current density (Jsc) and fill factor, attributing for suppressed nonradiative recombination. Moreover, it shows relative improvement in the stability of the device. The results of this finding reveal that using oligothiophene copolymer can enhance the photovoltaic performance and the stability of inverted OIHPSCs in the ambient environment. [ABSTRACT FROM AUTHOR]

Organic field effect transistors (OFETs) have been an innovate field of research in many ways, starting from the synthesis of organic molecular and polymeric semiconductors, to exploring various device architectures for diverse fabrication methods and finally to establishing practical applications such as bio-electronic sensors, ion pumps, bio-integrated circuits, etc. These achievements have been possible because of the special properties of organic semiconductors, one of them being the easy, versatile, low energy device fabrication, due to inherently lower processing temperatures of organic materials compared to their inorganic counterparts. In this paper, we introduce a group of industrial vat orange dyes in OFETs, i.e. vat orange 1, vat orange 3 and vat orange 9, and investigate their processability and material properties via cyclic voltammetry, FTIR, UV-Vis spectroscopy, X-ray diffraction, photoluminescence, film forming characteristics by atomic force microscopy, and finally look into their charge transport in fabricated organic field effect transistors. These materials that have natural quinone moieties are highly appealing for future investigations in organic electronics applications including field effect transistors, solar cells and electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Using the reverse micelle synthesis route, polystyrene-b-2vinylpyridine (PS-b-P2VP) diblock copolymers are used to synthesize hybrid perovskite nanoparticles with an ionic organic liquid five-membered heterocycle cation, pyrrolidinium (Py) (C4H8NH). Uniform, well-dispersed, and luminescent nanoparticles were fabricated with high stability due to the hydrophobic nature of Py and polymer encapsulation. The substitution of bromine for iodine induces a bathochromic shift, resulting in a substantial Stokes shift of 764 meV (211 nm) for mixed halide phase nanoparticles, contrary to the anticipated hypsochromic shift with bromine doping. This unique attribute of Py-based perovskites positions them as promising candidates for down-conversion applications in low-band-gap organic solar cells. Incorporating Py-based perovskite nanoparticles into bulk heterojunction organic photovoltaics (OPVs) as down-conversion layers selectively enhances the short-circuit current from UV components in the illumination source. The observed improvements in stability, uniformity, and luminescence, coupled with the distinct Stokes shift, underscore the potential of Py-based perovskite nanoparticles as a valuable component in improving the efficiency of OPVs. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) is identified as a promising reagent for fuel cells, reducing the dependency on carbon‐based fuels. In this work, electrochemically synthesized polymers are employed to improve the efficiency of the oxygen (O2) reduction reaction, thus producing H2O2 in an environmentally friendly way. Two aminoanthraquinones, as well as riboflavin (vitamin B2), are successfully immobilized via oxidative electropolymerization onto both glassy carbon and carbon paper. Of the investigated compounds, polyriboflavin shows a high Faradaic efficiency toward O2 reduction, even at a very low potential of only −0.1 V versus SHE. This catalytic effect is present in neutral and alkaline conditions, using both glassy carbon and carbon paper, but highly pronounced in neutral, aqueous solutions. [ABSTRACT FROM AUTHOR]

Surface‐enhanced Raman scattering (SERS) is a sensitive and fast technique for sensing applications such as chemical trace analysis. However, a successful, high‐throughput practical implementation necessitates the availability of simple‐to‐use and economical SERS substrates. In this work, we present a robust, reproducible, flexible and yet cost‐effective SERS substrate suited for the sensitive detection of analytes at near‐infrared (NIR) excitation wavelengths. The fabrication is based on a simple dropcast deposition of silver or gold nanomaterials on an aluminium foil support, making the design suitable for mass production. The fabricated SERS substrates can withstand very high average Raman laser power of up to 400 mW in the NIR wavelength range while maintaining a linear signal response of the analyte. This enables a combined high signal enhancement potential provided by (i) the field enhancement via the localized surface plasmon resonance introduced by the noble metal nanomaterials and (ii) additional enhancement proportional to an increase of the applicable Raman laser power without causing the thermal decomposition of the analyte. The application of the SERS substrates for the trace detection of melamine and rhodamine 6G is demonstrated, which shows limits of detection smaller than 0.1 ppm and analytical enhancement factors on the order of 104 as compared to bare aluminium foil. [ABSTRACT FROM AUTHOR]

Herein, the magnetic field effect on the source–drain current of organic field‐effect transistors with semiconductor layers made of H‐bonded pigments is studied. In all devices, an external magnetic field reduces the source–drain current in the transistor. The magnetic field effect is independent of the direction of the applied magnetic field. The observed increase of the magnetoresistance seems to originate from the used semiconductor or the semiconductor–dielectric interface and is not influenced by the nature of the gate electrodes or the semiconductors' deposition procedure (e.g., grain size, layer thicknesses, etc.). As all prepared devices do have single charge carrier nature, the formation of bipolarons is suggested to be responsible for the observed magnetic field effect. The presented experiments demonstrate that hydrogen‐bonded semiconductors behave no different than their classical van der Waals‐bonded fully conjugated semiconductors' counterparts. [ABSTRACT FROM AUTHOR]

Homogeneous, aqueous solutions of the natural compound riboflavin were investigated for their electrocatalytic oxygen to hydrogen peroxide (H2O2) reduction performance using cyclic voltammetry and electrolysis. In addition to pH dependencies, interestingly the choice of carbon‐based electrode material had a strong impact on the electrocatalytic performance. Therefore, the three electrode materials, glassy carbon, carbon paper (CP), and carbon felt were electrochemically compared and afterwards investigated with scanning electron microscopy. Attributed to the deprotonation of riboflavin, pH = 13 was identified as the best performing condition. Using CP at pH = 13, the addition of riboflavin enhanced the H2O2 production by a factor of 14 up to 355 μmol after 6 h at an average faradaic efficiency of around 80%. [ABSTRACT FROM AUTHOR]

Natural dielectrics are emerging nowadays as a niche selection of materials for applications targeting biocompatibility and biodegradability for electronics and sensors within the overall effort of scientific community to achieve sustainable development and to build environmental consciousness. The two natural resins analyzed in this study, silver fir and Rocky mountain fir demonstrate robust dielectric properties and excellent film forming capabilities, while being trap free dielectrics in high‐performance organic field effect transistors (OFETs) operating at voltages as low as 1 V. Immense research possibilities are demonstrated through the avenue of inorganic nanofillers insertions in the natural resins film, that opens the door for fabrication of very low voltage OFETs with high dielectric constant insulating layers. [ABSTRACT FROM AUTHOR]

This research presents a new series of tetrabenzoporphyrins (TBPs) bearing p‐diphenylaminophenylethynyl and p‐carboxylphenylethynyl groups or two p‐carboxylphenylethynyl groups in a trans‐fashion on a TBP core for photoelectrochemical O2 reduction. Impact of electron‐donating diphenylamino and electron‐withdrawing surface‐anchoring carboxyl groups on photophysical and electrochemical properties of the target TBPs was experimentally and theoretically investigated in comparison with those of their benchmark analog. The results show that while the p‐carboxylphenylethynyl group give an electronic contribution to the molecules by lowering energy gap, the role of the p‐diphenylaminophenylethynyl group is found to be trivial. Preliminary investigation on electrochemical O2 reduction indicates significant catalytic activities of TBP‐modified TiO2/fluorene‐doped tin oxide electrodes at potentials of −0.2 V and −0.3 V vs. normal hydrogen electrode (NHE) in a pH‐neutral and ambient aqueous condition, leading to H2O2 formation. Upon photoirradiation, catalytic performance of such TBP‐based electrodes is further enhanced with the optimum yield obtained when the dicarboxyl derivatives and the potential of −0.3 V vs. NHE are applied. Proposed photoinjection mechanism of the dye/TiO2 simulated by time‐dependent density functional theory calculations supported the experimental results indicating the favorable role of the target TBPs as photoelectrocatalysts in the O2 reduction. [ABSTRACT FROM AUTHOR]

Millions of people worldwide are diagnosed with retinal dystrophies such as retinitis pigmentosa and age-related macular degeneration. A retinal prosthesis using organic photovoltaic (OPV) semiconductors is a promising therapeutic device to restore vision to patients at the late onset of the disease. However, an appropriate cytotoxicity approach has to be employed on the OPV materials before using them as retinal implants. In this study, we followed ISO standards to assess the cytotoxicity of D18, Y6, PFN-Br and PDIN individually, and as mixtures of D18/Y6, D18/Y6/PFN-Br and D18/Y6/PDIN. These materials were proven for their high performance as organic solar cells. Human RPE cells were put in direct and indirect contact with these materials to analyze their cytotoxicity by the MTT assay, apoptosis by flow cytometry, and measurements of cell morphology and proliferation by immunofluorescence. We also assessed electrophysiological recordings on mouse retinal explants via microelectrode arrays (MEAs) coated with D18/Y6. In contrast to PFN-Br and PDIN, all in vitro experiments show no cytotoxicity of D18 and Y6 alone or as a D18/Y6 mixture. We conclude that D18/Y6 is safe to be subsequently investigated as a retinal prosthesis. [ABSTRACT FROM AUTHOR]

Anthraquinone (AQ) has long been identified as a highly promising lead structure for various applications in organic electronics. Considering the enormous number of possible substitution patterns of the AQ lead structure, with only a minority being commercially available, a systematic experimental screening of the associated electrochemical potentials represents a highly challenging and time consuming task, which can be greatly enhanced via suitable virtual pre-screening techniques. In this work the calculated electrochemical reduction potentials of pristine AQ and 12 hydroxy- or/and amino-substituted AQ derivatives in N,N-dimethylformamide have been correlated against newly measured experimental data. In addition to the calculations performed using density functional theory (DFT), the performance of different semi-empirical density functional tight binding (DFTB) approaches has been critically assessed. It was shown that the SCC DFTB/3ob parametrization in conjunction with the COSMO solvation model provides a highly adequate description of the electrochemical potentials also in the case of the two-fold reduced species. While the quality in the correlation against the experimental data proved to be slightly inferior compared to the employed DFT approach, the highly advantageous cost-accuracy ratio of the SCC DFTB/3ob/COSMO framework has important implications in the formulation of hierarchical screening strategies for materials associated with organic electronics. Based on the observed performance, the low-cost method provides sufficiently accurate results to execute efficient pre-screening protocols, which may then be followed by a DFT-based refinement of the best candidate structures to facilitate a systematic search for new, high-performance organic electronic materials. [ABSTRACT FROM AUTHOR]

Strategies for production and use of nanomaterials have rapidly moved towards safety and sustainability. Beyond these requirements, the novel routes must prove to be able to preserve and even improve the performance of the resulting nanomaterials. Increasing demand of high-performance nanomaterials is mostly related to electronic components, solar energy harvesting devices, pharmaceutical industries, biosensors, and photocatalysis. Among nanomaterials, Zinc oxide (ZnO) is of special interest, mainly due to its environmental compatibility and vast myriad of possibilities related to the tuning and the enhancement of ZnO properties. Doping plays a crucial role in this scenario. In this work we report and discuss the properties of undoped ZnO as well as lanthanide (Eu, Tb, and La)-doped ZnO nanoparticles obtained by using whey, a by-product of milk processing, as a chelating agent, without using citrate nor any other chelators. The route showed to be very effective and feasible for the affordable large-scale production of both pristine and doped ZnO nanoparticles in powder form. [ABSTRACT FROM AUTHOR]

Millimeter‐long organic fiber arrays of intramolecular charge transfer merocyanine HB194 dye were prepared by evaporation‐induced self‐assembled method. X‐ray diffraction spectroscopy indicated individual fibers are millimeter‐sized HB194 single crystals. The elimination of defects and structural disorder enabled photoluminescence microscopy studies that revealed the intramolecular charge transfer (CT), bandgap excitonic state is long‐lived and remains largely localized in the absence of π‐orbital stacking in the crystalline structure. These nanosecond lifetimes explain the observation of a photoconductivity response upon irradiation with a 633 nm laser due to dissociation of the delocalized CT exciton to free carriers. At the same time, the photo response was increased 4.5 times by coating of the HB194 fiber array with polyvinyl alcohol. This increase is attributed to the larger dielectric field around the fibers that further facilitates the band‐gap (CT) exciton dissociation. [ABSTRACT FROM AUTHOR]

Organic electronic devices rely on the performance of polymers that are used as active layers. Poly-(3,4-ethylenedioxythiophene) (PEDOT) is one of the most studied polymers for organic electronic devices and especially bioelectronics. Because charge carriers move along the polymer backbone (anisotropic charge transport), one of the key challenges is controlling orientation of the polymer in thin films, hence increasing the transport performance. Here, we introduce a method for the oriented growth of PEDOT chains on nanometer-thick self-assembled monolayer (SAM)-modified gold electrodes. We show that, when the gold layer is covered with a SAM that is active for polymer chain growth, a more crystalline film is obtained compared to the surface having a nonactive SAM. We used a nitric acid oxidant to perform the polymerization, which overcomes temperature incompatibility between the gold-supported thiolate monolayers and the polymerization. We characterize the chemical nature and physical properties of the oriented PEDOT film. Reaction conditions and ease of processing appeal especially to organic electronic device applications where surface modification can play a critical role. [ABSTRACT FROM AUTHOR]

The synthesis, experimental and theoretical study of the novel air‐stable four adamantane‐bearing dyes based on the trans‐epindolidione (EPI) and trans‐quinacridone (QA) cores are presented. Compared to the parent EPI and QA, the methyl‐/ethyladamantyl substitution ensures that their structural stability in crystals is preserved due to the self‐organizing properties of adamantyl groups. The investigated materials are solution‐processable in common organic solvents and possess excellent thermal stability. The very good solubility was achieved by a one‐step short and easy synthesis, which resulted in moderate yields of a new family of synthesized dyes. The ethyladamantyl EPI derivative (3) exhibits a unique rise in thermal stability reaching 412 °C. The resulting electrochemical band gap carried out on thin‐film evaporated on ITO‐coated glass electrodes was in the range of 2.4–2.5 eV. The experimental HOMO energies range from −6.2 to −6.0 eV, and LUMO energies lay between −3.7 and −3.5 eV. The prepared compounds are characterized by strong fluorescence in solutions and in powder, suggesting a decrease in the extent of non‐radiative relaxation processes. [ABSTRACT FROM AUTHOR]

The majority of energy storage devices like batteries, fuel cells or electrolyzers require heterogeneous electrodes. Immobilization of redox‐active organic molecules by a polymeric approach seems to be a promising route towards organic electrodes for electrocatalytic energy storage or in batteries. Although numerous reports on synthesis and application of new poly‐anthraquinones exist, a universal guideline or tool for selection of the best polymer, concerning several energy storage applications, is still underdeveloped. Moving into the direction of developing such a tool, we have selected and synthesized three poly(anthraquinones). NMR, FTIR, UV‐Vis, TGA, contact angle measurement and SEM revealed certain structure‐property trends, which can be correlated with the performance in the electrochemical investigation. The insights gained within this work demonstrate correlations between the FTIR frequencies and the electrochemical reduction potential, as well as between the polymer hydrophobicity and the electrochemical performance. [ABSTRACT FROM AUTHOR]

Important parameters of an organic semiconductor material are the electronic band gap (Eg) and the position of highest occupied and lowest unoccupied bands versus vacuum. These bands are called valence and conduction band for inorganic semiconductors. For organic semiconductors the bands defining the band gap are often called highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). One advantage of semiconducting polymers is the ability to tune the band gap and the position of HOMO and LUMO levels by molecular chemical design. The organic photovoltaic solar cells need absorbers with a smaller bandgap to maximize the power conversion efficiency of these devices. There are several chemical strategies to synthesize low band gap polymers for optoelectronic applications. In this manuscript, an updated overview on the current status of these low band gap conjugated polymers will be given. The design principles of low band gap polymers, the properties of the resulting materials, and important applications and devices realized with this material class will be briefly discussed. [ABSTRACT FROM AUTHOR]

X‐ray detectors play a pivotal role in development and advancement of humankind, from far‐reaching impact in medicine to furthering the ability to observe distant objects in outer space. While other electronics show the ability to adapt to flexible and lightweight formats, state‐of‐the‐art X‐ray detectors rely on materials requiring bulky and fragile configurations, severely limiting their applications. Lead halide perovskites is one of the most rapidly advancing novel materials with success in the field of semiconductor devices. Here, an ultraflexible, lightweight, and highly conformable passively operated thin film perovskite X‐ray detector with a sensitivity as high as 9.3 ± 0.5 µC Gy−1 cm−2 at 0 V and a remarkably low limit of detection of 0.58 ± 0.05 μGy s−1 is presented. Various electron and hole transporting layers accessing their individual impact on the detector performance are evaluated. Moreover, it is shown that this ultrathin form‐factor allows for fabrication of devices detecting X‐rays equivalently from front and back side. [ABSTRACT FROM AUTHOR]

The issue of long‐term stability is one of the main obstacles challenging the progress of perovskite solar cells (PSCs). To alleviate this issue, a thorough understanding of the degradation mechanisms of the device is required. Herein, electrochemical impedance measurements in combination with maximum power point (MPP) tracking are applied to characterize PSCs, aiming to gain an understanding of the charge carrier dynamics in the photoactive bulk and at the contact‐absorber‐interfaces under operation. Electrochemical impedance spectroscopy (EIS) results show that the device charge transport resistance and interface capacitance associated with charge accumulation at the interfaces are both increasing upon continuous operation. This suggests ion migration from the photoactive perovskite layer to the charge transport layer interfaces leaving defects in the bulk. This suggests that reduction of the device performance upon continuous operation is mainly related to the changes in the bulk of the photoactive perovskite film and ions migration. [ABSTRACT FROM AUTHOR]

In this work, two novel ZnII- and CoII-porphyrin monomers with thiophene-based units attached via flexible 1,3-aminothiopropylene linkers were successfully synthesized and fully characterized. Electropolymerization of these monomers was performed on indium tin oxide (ITO)-coated glass and carbon paper via cyclic voltammetry (CV) to obtain the corresponding polymer films for photophysical characterization and investigation of their catalytic activities for the electrochemical reduction (ECR) of carbon dioxide (CO2), respectively. CV and controlled potential electrolysis (CPE) in a 0.5 M KHCO3 aqueous solution showed that the ZnII-porphyrin-based polymer mainly supports hydrogen (H2) evolution from water splitting, while the CoII-porphyrin-based polymer predominately promotes the formation of carbon monoxide (CO). At a reduction potential of −0.66 V vs. reversible hydrogen electrode (RHE), equivalent to an overpotential of −0.54 V, CPE under the catalysis of the CoII-porphyrin-based polymer could efficiently convert CO2 to CO with the optimum faradaic efficiency, turnover number (TON) and turnover frequency (TOF) of 66%, 5.7 × 102 and 1.6 s−1, respectively, after 1 h. The 6 h CPE suggests satisfactory film stability and steady production of CO from the ECR of CO2, indicating the potential use of this polymer film for the reduction of CO2 at a low overpotential under ambient conditions in aqueous media. [ABSTRACT FROM AUTHOR]

In this work, the preparation of conducting polymer‐based composites using a biological anionic polymer based on salmon deoxyribonucleic acid (DNA) is presented. The most commonly used polymers poly(3,4‐ethylenedioxythiophene) (PEDOT), as well as polypyrrole, are polymerized in the presence of DNA. Since conjugated polymers are in the polycationic state in their electrically conducting form, the role of the counterion is now fulfilled by the low cost biomolecule DNA as an alternative material, which is also a polyanion thanks to its phosphate chain. The resulting synthesized material is a conducting polymer–DNA biocomposite. Such materials are highly attractive for the rising field of bioelectronics and biosensors, especially in organic electrochemical transistors (OECTs) and ion pumps. OECTs made of these conducting polymer biocomposites are fabricated and their electrochemical device operation is compared to the most widely used PEDOT:polystyrenesulfonate. [ABSTRACT FROM AUTHOR]

Here, a simple method for controlling the size of the perovskite nanoparticles (PNPs) during preparation is reported. Metal halide PNPs have great potential for application in optoelectronic devices, such as light-emitting diodes, lasers, photodetectors, etc. They have exceptionally high photoluminescence quantum yields (PLQYs) and exhibit chemical tunability for versatile modifications of the perovskite structural composition, enabling the synthesis of nanoparticles with controlled size, shape, and optical properties. In this work, methylammonium lead bromide PNPs were prepared using a hygroscopic stabilizing ligand, tert-butoxycarbonyl-Lysine (tboc-Lysine). Water was used as an additive in the precursor solution, which resulted in the formation of highly mobile species and, thus, the nhancement of perovskite lattice growth. This method allowed the preparation of PNPs with controlled size between 4 and 7 nm. The quantum confinement effect led to a fine-tuned optical band gap of the nanoparticles. Increasing the amount of water added from 0 to 32 mol equiv with respect to Lead-(II) bromide (PbBr2) increased the PLQY to 70% in colloidal solutions and to 87% in thin films. Therefore, because of control over the size and high luminescent yields, the above-mentioned nanoparticles are targeted for use in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Organic-based field-effect transistors (OFETs) utilize organic semiconductor materials with low electron mobilities and organic gate oxide materials with low dielectric constants. These have rendered devices with slow operating speeds and high operating voltages, compared with their inorganic silicon-based counter parts. Using a deoxyribonucleic acid (DNA)-based biopolymer, derived from salmon milt and roe sac waste by-products, for the gate dielectric region, we have fabricated an OFET device that exhibits very promising current-voltage characteristics compared with using other organic-based dielectrics. With minimal optimization, using a thin film of DNA-based biopolymer as the gate insulator and pentacene as the semiconductor, we have demonstrated a bio-organic-FET, or BiOFET, in which the current was modulated over three orders of magnitude using gate voltages less than 10 V. [ABSTRACT FROM AUTHOR]

Stable radicals in organic conjugated molecules are of great interest due to their magnetic signals and broad optical absorptions. In this paper, we report on naphthalene, benzoperylene, perylene, terrylene, and quaterrylene carboximides, reduced under controlled conditions, where stable metal-free solid salts of radical anions could be obtained forming darkly colored solutions with line-rich UV/Vis/NIR spectra and exhibiting special magnetic properties. The most bathochromic shift of the absorption maxima extend from 760 until 1700 nm. Persistent paramagnetic properties of the solids were observed and temperature-dependent susceptibilities are measured. [ABSTRACT FROM AUTHOR]

In order to account for a sustainable future technology, theapplication of biodegradable and biocompatible systems for organic opto electronics are needed. The use of cheap electronic devices in a large scale will introduce a "consumable electronics" into the market of "consumer electronics". Therefore environmentally friendly materials are important to use. This is a next great challenge to material science in organic electronics. New developments of bio-inspired and/or bio-origin, bio-compatible materials are reported. Such materials can also be used to interface the biological and biomedical research with the bioorganic electronics field. [ABSTRACT FROM AUTHOR]

Recently, we have reported that metal halide perovskite nanoparticles formed in nanoporous alumina and silicon thin films exhibit blue shifted photoluminescence due to spatial confinement, thus allowing for color tuning of the emission by varying the pore size. While perovskite nanoparticles grown in nanoporous alumina films have been integrated into LEDs, similar approaches have failed with silicon. Here, we report the results of investigating the structure of the alumina pore system and the perovskite crystallites forming within. We use two x-ray diffraction techniques, namely, small-angle x-ray scattering (SAXS) and high-energy microbeam wide-angle x-ray scattering (WAXS). SAXS reveals that the alumina pore system diffracts like regularly arranged tubes with the average diameter and nearest neighbor distance of 12 nm and 20 nm, respectively. High-energy microbeam WAXS shows that perovskite nanoparticles within the nanoporous alumina have a distinctly anisotropic shape with the average particle length along and perpendicular to the pore axis of 26 nm and 13 nm, respectively. In contrast, no shape anisotropy has been detected for nanoparticles inside the silicon pores in a previous study. This suggests that utilizing nanoporous alumina has a twofold advantage. First, the tubular alumina pores, spanning the entire insulating film, offer percolated paths for the perovskite to fill. Second, the elongation of the nanoparticles in the tubular alumina pores can be expected to aid device performance as the length of the nanoparticles approaches the active layer thickness (ca. 40 nm) of LEDs, while the small diameter of the crystallites accounts for the observed blue shifted emission. [ABSTRACT FROM AUTHOR]

Injection-charge extraction by linearly increasing voltage in metal-insulator-semiconductor structures (MIS-CELIV) is applied for the hole mobility measurement of N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB), which is a standard hole-transporting material for organic light-emitting diodes. Ideal transient currents in agreement with the theory are observed in the NPB film due to its amorphous and homogenous structure, which is regarded as a continuous dielectric. This ideal response enables us to discuss the validity of the MIS-CELIV mobility by comparing its absolute value with that of the conventional space-charge-limited current method. In addition, to establish an experimental guideline for precise measurements, the effect of the voltage drop on the insulator is investigated. [ABSTRACT FROM AUTHOR]

Flavins are known to be extremely versatile, thus enabling routes to innumerable modifications in order to obtain desired properties. Thus, in the present paper, the group of bio-inspired conjugated materials based on the alloxazine core is synthetized using two efficient novel synthetic approaches providing relatively high reaction yields. The comprehensive characterization of the materials, in order to evaluate the properties and application potential, has shown that the modification of the initial alloxazine core with aromatic substituents allows fine tuning of the optical bandgap, position of electronic orbitals, absorption and emission properties. Interestingly, the compounds possess multichromophoric behavior, which is assumed to be the results of an intramolecular proton transfer. [ABSTRACT FROM AUTHOR]

We report reversible electrochemical capture and release of carbon dioxide using the well-known dye precursor and industrial catalyst anthraquinone. Although quinones are well-studied for electrochemical capture and release of CO2 in solution, we have discovered that a 100 nm film of anthraquinone can realize this in a heterogeneous fashion. In-depth spectroelectrochemical studies were performed in order to study the mechanism of this CO2 capture and release. Anthraquinone films reached an uptake capacity of 5.9 mmolCO2 gAQ−1. [ABSTRACT FROM AUTHOR]

Abstract: We report on a self‐assembled system comprising a molecular copper‐porphyrin photoelectrocatalyst, 5‐(4‐carboxy‐phenyl)‐10,15,20‐triphenylporphyrinatocopper(II) (CuTPP‐COOH), covalently bound to self‐organized, anodic titania nanotube arrays (TiO2 NTs) for photoelectrochemical reduction of oxygen. Visible light irradiation of the porphyrin‐covered TiO2 NTs under cathodic polarization up to −0.3 V vs. Normal hydrogen electrode (NHE) photocatalytically produces H2O2 in pH neutral electrolyte, at room temperature and without need of sacrificial electron donors. The formation of H2O2 upon irradiation is proven and quantified by direct colorimetric detection using 4‐nitrophenyl boronic acid (p‐NPBA) as a reactant. This simple approach for the attachment of a small molecular catalyst to TiO2 NTs may ultimately allow for the preparation of a low‐cost H2O2 evolving cathode for efficient photoelectrochemical energy storage under ambient conditions. [ABSTRACT FROM AUTHOR]

Conductive polymers represent a rare case in which free-carrier absorption is shifted to the far-infrared-an attractive advantage in light of the requirement of highly transparent conductors across the visible and near-infrared. Unfortunately, prior approaches to doping these polymers-imperative for high conductance-have consistently led to strong localization arising from fluctuating band alignment among polymer chains. Here, this study overcomes this problem of doping-induced Anderson localization for the first time in polymers by developing a new conductive polymer synthesis strategy. This study achieves polymerization and doping simultaneously, thereby using an alternative nonmetal oxidant and thereby avoiding the introduction of excess energy that normally arises from exergonic polymerization. The resulting conductive polymer is the first to provide electron coherence in a metallic polymer thin film. The conductivity reaches a remarkable 3300 S cm−1 at 1.8 K and the mean electron scattering length a record 330 Å. This enhancement drives the glassy metal transition in the vicinity of the Mott-Ioffe-Regel (MIR) limit. The new metallic polymer achieves 10−2 Ω−1 figure of merit, making it a contender for transparent conductive contacts previously only accessible using inorganics. The new material offers a uniquely broad transparency window spanning the UV to the mid-infrared. [ABSTRACT FROM AUTHOR]

Successful formation of electronic interfaces between living cells and semiconductors hinges on being able to obtain an extremely close and high surface-area contact, which preserves both cell viability and semiconductor performance. To accomplish this, we introduce organic semiconductor assemblies consisting of a hierarchical arrangement of nanocrystals. These are synthesised via a colloidal chemical route that transforms the nontoxic commercial pigment quinacridone into various biomimetic three-dimensional arrangements of nanocrystals. Through a tuning of parameters such as precursor concentration, ligands and additives, we obtain complex size and shape control at room temperature. We elaborate hedgehog-shaped crystals comprising nanoscale needles or daggers that form intimate interfaces with the cell membrane, minimising the cleft with single cells without apparent detriment to viability. Excitation of such interfaces with light leads to effective cellular photostimulation. We find reversible light-induced conductance changes in ion-selective or temperature-gated channels. [ABSTRACT FROM AUTHOR]

Novel ethyladamantyl solubilization side groups were found to induce π–π interactions between the conjugated cores through adamantyl–adamantyl stacking in soluble diketopyrrolopyrrole (DPP) derivatives. The closeness of the DPP cores amplifies charge transfer in the material, as far as the π–π interaction is a dominant charge-hopping pathway. As a result, tenfold enhancement of hole mobilities exceeding those obtained for insoluble derivatives was reached. Moreover, due to high crystallinity and co-planarity of the conjugated cores, electron transfer was preserved with a mobility of 0.2 cm2 V−1 s−1 for dithiophene-DPP. At the same time, the material remained soluble, which is a significant advantage for purification and processing. This approach can be universally applied for many types of semiconducting organic materials containing the imide motif, where solubilization is achieved by side-group substitution. [ABSTRACT FROM AUTHOR]

We report on the fabrication and opto-electronic characterization of solution-processed planar heterojunction perovskite solar cells based on methylammonium (MA) lead halide derivatives, MAPbI3−xYx (Y = Cl, Br, I). Dissolving equimolar amounts of lead iodide (PbI2) and methylammonium iodide (H3CNH3I) together with various amounts of additional methylammonium halides, perovskite precursor solutions were obtained, which were used in the fabrication of three perovskite systems, MAPbI3, MAPbI3−xClx and MAPbI3−xBrx. The effect of the halide ratio in the perovskite formulations processed via a one-step deposition technique on optoelectronic properties and on photovoltaic performance of the formed perovskites was investigated. The perovskite film morphology, temperature-dependent photoluminescence properties, hysteresis behaviour in current–voltage characteristics and the photovoltaic performance as a function of chemical composition were studied using microscopic, spectroscopic and photovoltaic characterization techniques. The power conversion efficiency was found to be dependent on MAPbI3−xYx (Y = Cl, Br, I) perovskite film morphology. By controlling perovskite precursor composition and stoichiometry, highest power conversion efficiencies of 9.2, 12.5 and 5.4% were obtained for MAPbI3, MAPbI3−xClx and MAPbI3−xBrx devices, respectively. In addition, the physical parameters of the mixed halide perovskites such as the exciton binding energy, exciton–phonon interaction and bandgap were determined via temperature-dependent photoluminescence spectroscopy. Exciton binding and optical phonon energies of MAPbI3−xYx (Y = Cl, Br, I) were found to be in the ranges of 49–68 meV and 29–32 meV respectively. The solution-processed MA lead halide derivatives form highly crystalline materials with chemical versatility allowing the tuning of their optical and electronic properties depending on the nature and the ratio of the halides employed. [ABSTRACT FROM AUTHOR]

Carbon dioxide has evolved from being considered as a greenhouse gas to a valuable carbon feedstock for the generation of artificial fuels and valuable chemicals. In this work, we review the biocatalytic approaches towards CO2 conversion into chemicals and fuels. We display the opportunities and challenges of using biocatalysts. Our work especially focuses on bio-electrocatalytic systems. These electrochemical applications of biocatalysts gain increasing interest, as electrochemical redox processes can avoid expensive mediators and co-factors. This is also a pathway for renewable energy storage because wind or solar energy can possibly be applied as electrical sources for the electrochemical CO2 conversion systems. Biocatalytic CO2 conversion together with renewable energy storage represents a viable and sustainable route for the generation of chemicals and fuels. [ABSTRACT FROM AUTHOR]

We present a study on a microbial electrolysis cell with methanogenic microorganisms adapted to reduce CO2 to CH4 with the direct injection of electrons and without the artificial addition of H2 or an additional carbon source except gaseous CO2. This is a new approach in comparison to previous work in which both bicarbonate and gaseous CO2 served as the carbon source. The methanogens used are known to perform well in anaerobic reactors and metabolize H2 and CO2 to CH4 and water. This study shows the biofilm formation of those microorganisms on a carbon felt electrode and the long-term performance for CO2 reduction to CH4 using direct electrochemical reduction. CO2 reduction is performed simply by electron uptake with gaseous CO2 as the sole carbon source in a defined medium. This 'electrometabolism' in such microbial electrolysis cells depends strongly on the potential applied as well as on the environmental conditions. We investigated the performance using different adaption mechanisms and a constant potential of −700 mV vs. Ag/AgCl for CH4 generation at 30-35 °C. The experiments were performed by using two-compartment electrochemical cells. Production rates with Faradaic efficiencies of around 22 % were observed. [ABSTRACT FROM AUTHOR]