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The use of nanostructured materials is increasingly widespread thanks to their particular properties that can improve the performance of devices in various scientific applications. One of them is in the architecture of perovskite solar cells characterized by high photoconversion efficiency values that make them able to compete with silicon solar cells. In this framework, we deposited TiO[Formula: see text] sponges by reactive sputtering based on a grazing-incidence geometry combined with the local oxidation of species. The deposited material gains 50% porosity in volume through depths of hundreds of nanometers and consists of a forest of uniform rods separated by mesopores (pipelines) arising from the grazing geometry. Many previous studies showed how TiO[Formula: see text] can improve the efficiency of perovskite solar cells. In this article, we investigated the change of the wettability values of the TiO[Formula: see text] samples before and after a postdeposition thermal annealing treatment. For comparison, the influence of the annealing on the wettability of the glass substrate is also reported.

In the field of photovoltaics (PV), an important trend is to increase the aesthetic and creative design aspects of solar cells towards more attractive and customized devices for integration in for instance architecture, e.g. building integrated photovoltaics (BIPV). Here we introduce the concept of "photovoltaic photographs", defined as semi-transparent solar cells (STSC) that are treated with a light-induced process to integrate an image in the photoactive layer, allowing creative applications such as photovoltaic photographs, paintings, posters, etc. Contrary to previously reported patterning processes used in emerging photovoltaics such as inkjet printing or methods where patterned transparent foils are assembled on top of the solar cells, the approach proposed here to obtain a patterned 2D-photoactive layer, is by using a direct photo-induced patterning process based on photobleaching of chromophores. Proof-of-principle demonstrators have been realized using dye-sensitized solar cells and the obtained insights can open the way to the exploration of combining this concept with other PV technologies. The authors thank the colleagues from X-LAB from UHasselt for discussions and feedback. Special thanks to M. De Roeve for help with the experimental setup. This research was supported by the Research Foundation – Flanders (FWO) with research project G089918N (J.H. and J.M.) and PhD Fellowship with application number 11K4322N (N.F.).

The introduction of an electron-donating triphenylamine motive into a 2,2′,6′,2′′-terpyridine (terpy) moiety, a cornerstone molecular unit in coordination chemistry, opens new ways for a rational design of photophysical properties of organic and inorganic compounds. A push-pull compound, 4′-(4-(di(4-tert-butylphenyl)amine)phenyl)-2,2′,6′,2′′-terpyridine (tBuTPAterpy), was thoroughly investigated with the use of steady-state and time-resolved spectroscopies and Density Functional Theory (DFT) calculations. Our results demonstrate that solvent parameters have an enormous influence on the optical properties of this molecule, acting as knobs for external control of its photophysics. The Intramolecular Charge Transfer (ICT) process introduces a remarkable solvent polarity effect on the emission spectra without affecting the lowest absorption band, as confirmed by DFT simulations, including solvation effects. The calculations ascribe the lowest absorption transitions to two singlet ICT excited states, S1 and S2, with S1 having several orders of magnitude higher oscillator strength than the “dark” S2 state. Temperature and viscosity investigations suggest the existence of two emitting excited states with different structural conformations. The phosphorescence emission band observed at 77 K is assigned to a localized 3terpy state. Finally, protonation studies show that tBuTPAterpy undergoes a reversible process, making it a promising probe of the pH level in the context of acidity determination.

Quantum Dot Sensitized Solar Cells (QDSSC) is one of the most focused energy sources among the 3rd generation energy sources with the theoretically promised energy conversion efficiency. Even though the experimental studies have been far from the maximum efficiency that should be obtained theoretically, efficiency continues to increase rapidly with new application and treatment methods. One of the problems to be solved in QDSSC technology is the selection of the counter electrode (CE) and electrolyte that is compatible with the synthesized QD, and the studies on this subject are limited compared to other studies. In this study, CdSeTe QDSSCs were designed in combination with 3 different CE (Au, Pt, Cu2S) and 2 different electrolytes (triiodide, polysulfide) and the effects of CEs on QDSSC performance were compared. As a result of the study, it was determined that the use of Cu2S CE/polysulfide electrolyte in the design of CdSeTe QDSSS increased PCE up to 1.408%. The highest filling factor (FF) and highest V-oc values were obtained by Pt CE/triiodide electrolyte in these studies and these values were 60.664% and 0.730 V, respectively. Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [217M897] This study was financially supported by Scientific and Technological Research Council of Turkey (TUBITAK), project number 217M897. WOS:000514747600046 2-s2.0-85078032920

Imidazolium-based ionic liquids (ILs) with allyl and ether side chains were synthesized and characterized. Comprehensive structural and photoelectrochemical characterizations were performed, transport properties of ILs were also examined as electrolyte components in dye sensitized solar cells (DSSCs). The properties of synthesized materials and DSSC performances were compared with 1-propyl-3-methyl imidazolium iodide (PMII) and 1-allyl-3-ethyl imidazolium iodide (AEII) as reference ILs. Ionic conductivities, diffusion coefficients and charge transfer resistances of synthesized ionic liquids were investigated on DSSCs by Electrochemical Impedance Spectroscopy (EIS). The diffusion coefficient values of triiodide ions in different ionic liquid-based electrolytes were measured by the means of diffusion limited current density method and found to be 1.75x10(-7) cm(2) s(-1) and 2.05x10(-7) cm(2) s(-1) with corresponding photocurrent densities of 10.38 mAcm(-2) and 12.13 mAcm(-2) for the reference AEII and PMII based electrolytes, respectively. However, for the electrolytes of 1-(2-methoxyethyl)-3-allyl imidazolium iodide and 1-allyl-3-methyl imidazolium iodide ionic liquids, these values were found to be 0.86x10(-7) cm(2) s(-1) and 0.57x10(-7) cm(2) s(-1) with photocurrent densities of 9.53 mAcm(-2) and 8.98 mAcm(-2), respectively. Allyl and ether substituted imidazolium ILs exhibited promising results as potential alternative electrolyte materials for DSSCs., Ege University [09GEE10, 10GEE008]; Presidency of Turkey [2016 K12-2841], We would like to acknowledge Ege University research project funds with the contract numbers of 09GEE10 and 10GEE008. Authors acknowledge to Presidency of Turkey, Presidency of Strategy and Budget for supporting of laboratory infrastructure of Solar Energy Institute with Grant Nr: 2016 K12-2841. We would also like to thank Dr H. Q. Nimal Gunaratne, Prof Dr Kenneth R. Seddon and the QUILL Research Centre (Queen's University Ionic Liquid Laboratories) for their contributions on the synthesis and characterization of the ILs.

The relatively low symmetry of [3,3'-Co(1,2-C2B9H11)2]- ([1]-), along with the high number of available substitution sites, 18 on the boron atoms and 4 on the carbon atoms, allows a fairly regioselective and stepwise chlorination of the platform and therefore a very controlled tuning of the electrochemical potential tuning. This is not so easily found in other systems, e.g., ferrocene. In this work, we show how a single platform with boron and carbon in the ligand, and only cobalt can produce a tuning of potentials in a stepwise manner in the 1.3 V range. The platform used is made of two icosahedra sharing one vertex. The E1/2 tuning has been achieved from [1]- by sequential chlorination, which has given potentials whose values increase sequentially and linearly with the number of chloro groups in the platform. [Cl8-1]-, [Cl10-1]-, and [Cl12-1]- have been obtained, which are added to the existing [Cl-1]-, [Cl2-1]-, [Cl4-1]-, and [Cl6-1]- described earlier to give the 1.3 V range. It is envisaged to extend this range also sequentially by changing the metal from cobalt to iron. The last successful synthesis of the highest chlorinated derivatives of cobaltabis(dicarbollide) dates back to 1982, and since then, no more advances have occurred toward more substituted metallacarborane chlorinated compounds. [Cl8-1]-, [Cl10-1]-, and [Cl12-1]- are made with an easy and fast method. The key point of the reaction is the use of the protonated form of [Co(C2B9H11)2]-, as a starting material, and the use of sulfuryl chloride, a less hazardous and easier to use chlorinating agent. In addition, we present a complete, spectroscopic, crystallographic, and electrochemical characterization, together with a study of the influence of the chlorination position in the electrochemical properties., We gratefully acknowledge the Spanish Ministerio de Economía y Competitividad (Grant PID2019-106832RB-I00) and Generalitat de Catalunya (Grant 2017SGR1720). A.B.B. was enrolled in the Ph.D. program of UAB., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

The continued development of solar energy conversion technologies relies on an improved understanding of their limitations. In this review, we focus on a comparison of the charge carrier dynamics underlying the function of photovoltaic devices with those of both natural and artificial photosynthetic systems. The solar energy conversion efficiency is determined by the product of the rate of generation of high energy species (charges for solar cells, chemical fuels for photosynthesis) and the energy contained in these species. It is known that the underlying kinetics of the photophysical and charge transfer processes affect the production yield of high energy species. Comparatively little attention has been paid to how these kinetics are linked to the energy contained in the high energy species or the energy lost in driving the forward reactions. Here we review the operational parameters of both photovoltaic and photosynthetic systems to highlight the energy cost of extending the lifetime of charge carriers to levels that enable function. We show a strong correlation between the energy lost within the device and the necessary lifetime gain, even when considering natural photosynthesis alongside artificial systems. From consideration of experimental data across all these systems, the emprical energetic cost of each 10-fold increase in lifetime is 87 meV. This energetic cost of lifetime gain is approx. 50% greater than the 59 meV predicted from a simple kinetic model. Broadly speaking, photovoltaic devices show smaller energy losses compared to photosynthetic devices due to the smaller lifetime gains needed. This is because of faster charge extraction processes in photovoltaic devices compared to the complex multi-electron, multi-proton redox reactions that produce fuels in photosynthetic devices. The result is that in photosynthetic systems, larger energetic costs are paid to overcome unfavorable kinetic competition between the excited state lifetime and the rate of interfacial reactions. We apply this framework to leading examples of photovoltaic and photosynthetic devices to identify kinetic sources of energy loss and identify possible strategies to reduce this energy loss. The kinetic and energetic analyses undertaken are applicable to both photovoltaic and photosynthetic systems allowing for a holistic comparison of both types of solar energy conversion approaches.

Developing a high-performance catalyst and establishing a catalytic mechanism for understanding the catalytic activity are crucial to new generation photovoltaic technology. In this work, we present a feasible and general route to synthesize a bio-based porous carbon (BPC) supported ZnNb2O6 hybrid catalyst with a unique network structure, providing an effective means for electron transport between the electrode and the external circuit. Benefitting from the synergistic effect of ZnNb2O6 and BPC, a photovoltaic device assembled with the nanohybrid yields a power conversion efficiency of 8.83%, which is superior to that of pristine ZnNb2O6-based and conventional Pt-based cells (7.15% and 7.14%). Systematic electrochemical evaluations of the hybrid catalysts exhibit promising stability for practical application in photovoltaics. Contraposing the two vital functions of the counter electrode catalyst, collecting electrons and catalyzing I-3(-) reduction, we propose a general strategy to understand the potential catalytic mechanism from the band structure and surface adsorption by using first-principles density functional theory (DFT) calculations. The theoretical investigations clearly indicate that the splendid catalytic performance originates from the zero band-gap of surface metal atoms and the surface chemical adsorption interaction between I-3(-) and exposed metal atoms. The proposed general strategy in this work for synthesizing a hybrid material with a unique network structure and understanding the catalytic mechanism of the electrocatalyst can guide the design of expected catalytic nanohybrids applied in various energy fields.

Dye solar cells (DSCs) are gaining increasing interest since the recent realization of their high-performance potential in low/indoor light environments. Fused conjugated metal-free organic dyes have become a prominent class of dyes used in DSC in recent times by virtue of their better backbone rigidity, efficient charge transport properties, and the opportunity they provide for further structural modifications. Herein, we report the synthesis and characterization of three metal-free D–π–A organic dyes employing indolo[3,2-b]indole as the donor unit. The optical, electrochemical and photovoltaic properties have been analyzed in detail as a function of π-spacers, namely, benzene (IID-1), thiophene (IID-2) and furan (IID-3). Eventually, the best performance was demonstrated by the dye bearing benzene as the π-spacer. The role of recombination in determining the photovoltaic performance as a function of the nature of π-spacers was explored in detail, using various perturbation techniques on the fabricated devices, and compared with the results obtained from molecular orbital calculations.

Gold quantum dots (GQDs) have significant applications in the biomedical field, solar cells and light-emitting diodes. Synthesis of three various types of blue fluorescent GQDs are carried out for the first time by Nd: YAG laser ablation of Au target in aromatic solvent. The laser fluence used in this experiment was 0.2 J/cm(2). The characteristics of the as-prepared GQDs are confirmed by UV-vis, transmittance electron microscopy, X-ray diffraction, photoelectron spectroscopy and photoluminescence (PL). Pure and ligand-free gold quantum dots as a new type of fluorescent material are prepared through a one-step novel method. The results suggest that the molecule-like structure of GQDs is proven by the optical band energy gap (E-g = 2.54 eV), PL (lambda(em) = 427 nm, 1.76% quantum yield) and quantum confinement of an ultra-tiny size (similar to 1 nm). GQDs particles size of about 1 nm obtained by laser ablation in aromatic medium are reported for the first time. The blue luminescent and high purity of GQDs can be used efficiently for important applications, such as biosensor, bioimaging and bio-diagnosis., (TUBITAK)/Department of Science Fellowships; Grant Programs (BIDEB)/2221; Ege University-solar Energy Institute; University of Technology/ ministry of higher education and scientific research, Baghdad-Iraq, This work was supported by (TUBITAK)/Department of Science Fellowships and Grant Programs (BIDEB)/2221 and by Ege University-solar Energy Institute. Further, it was supported by the University of Technology/ ministry of higher education and scientific research, Baghdad-Iraq. Thanks to Ege University/ Library and Documentation Center for English proof reading.

4-(9'-Hexylcarbazol-3'-yl)benzaldehyde (Cz-Ph-CHO: 4 ) and 4-(9'-hexylcarbazol-3'- yl)benzylidenemalononitrile (Cz-Ph-CN: 5 ) were synthesised with the structure of D-pi-A,where carbazole, phenylene and formyl/dicyanovinyl groups act as electron donor (D), pi-spacer (pi) and electron acceptor (A) units, respectively. The thermal, electrochemical, optical and intramolecular charge transfer (ICT) properties of compounds 4 and 5 were investigated. Compounds 4 and 5 , in particular their ICT behaviour, were also compared with the closely related structure, 2-(9'-hexylcarbazol-3'-yl)-5-pyridinecarbaldehyde (Cz-Py-CHO: 7 ). For the purpose of tuning chemical structure to obtain targeted properties, electrochemical data and absorption and emission measurements suggest that the dicyanovinyl unit in compound 5 is a better acceptor than formyl in compound 4, and that pyridine in compound 7 is a better pi-spacer than benzene in compound 4 , in exerting ICT characteristics such as fluorosolvatochromism and Stokes shifts. (C) 2021 Elsevier B.V. All rights reserved. Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); University of Glasgow; EPSRC ECR Capital Award SchemeUK Research & Innovation (UKRI)Engineering & Physical Sciences Research Council (EPSRC) [EP/S017984/1] Dr. Ahmet Battal thanks the Scientific and Technological Research Council of Turkey (TUBITAK) for 2219-International Postdoctoral Research Fellowship Programme for Turkish Citizens. Dr William Peveler acknowledges the University of Glasgow for an LKAS Scholarship and the EPSRC ECR Capital Award Scheme (EP/S017984/1) for the Duetta instrument.

In this work, a polymer electrolyte (PE) based on Poly (methyl methacrylate) PMMA doped with Ionic liquid (IL) 1-ethyl-3-methylimidazoliumtricyanomethanide (EMImTCM) was synthesized using solution cast method. The Addition of IL increases ionic conductivity and conductivity maximum (8.83 x 10(-5) S cm(-1)) observed at 30 wt% of IL concentration in polymer. Polarized optical microscopy(POM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), X-ray diffraction (XRD) were also done to reveal the amorphous region, composite nature, thermal stability, crystalline nature respectively of developed IL-doped polymer electrolyte (PE) films. At last, we have used the maximum IL doped (30 wt%) in polymer matrix, film sandwiched in between carbon based electrodes (reported elsewhere by our group) to develop an efficient supercapacitor which confirms the specific capacitance 130 mF/g. The photovoltaic performance fabricated dye sensitized solar cell (DSSC) using same optimized polymer electrolyte was carried out at 1 sun condition which shows short-circuit current voltage of 0.61 V and an efficiency of 3.54%.(c) 2022 Elsevier B.V. All rights reserved.

Quantum dots (QD) tend to exhibit low photoluminescence (PL) properties due to long hanging ligands on their surface and steric barriers resulting therefrom. On the other hand, in order to be used in QD LED and QDSSC technologies, highly intense PL characteristics and PL lifetime are required respectively. Therefore, this study focuses on increasing the PL QY and PL lifetime of CdSeTe alloy QDs. To achieve this aim, CdSeTe alloy QDs synthesized by organometallic method were treated with different mass % (m/m) chloride solution. The PL Quantum Yield (PL QY) of CdSeTe alloy QDs, which was 13.2 +/- 2.0% before treatment, increased to 97.4 +/- 2.0% after treatment with 60% CdCl2 solution approaching to almost unity value. In addition to the increase in PL QY, PL lifetime increased from 28 ns to 33 ns with chloride treatment. However, thanks to surface passivation, the time to fall to half the value of PL QY for treated CdSeTe(CI) QDs under oxygen exposure was increased from 10 h to 64 h. In the study, the absorbance and emission characterizations of CdSeTe alloy QDs treated with chloride and untreated, were presented. (C) 2019 Elsevier B.V. All rights reserved. Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [217M897] This study was financially supported by The Scientific and Technological Research Council of Turkey (TUBITAK), project number 217M897. WOS:000506166400157 2-s2.0-85074441769

Improving the long-term stability of perovskite solar cells is critical to the deployment of this technology. Despite the great emphasis laid on stability-related investigations, publications lack consistency in experimental procedures and parameters reported. It is therefore challenging to reproduce and compare results and thereby develop a deep understanding of degradation mechanisms. Here, we report a consensus between researchers in the field on procedures for testing perovskite solar cell stability, which are based on the International Summit on Organic Photovoltaic Stability (ISOS) protocols. We propose additional procedures to account for properties specific to PSCs such as ion redistribution under electric fields, reversible degradation and to distinguish ambient-induced degradation from other stress factors. These protocols are not intended as a replacement of the existing qualification standards, but rather they aim to unify the stability assessment and to understand failure modes. Finally, we identify key procedural information which we suggest reporting in publications to improve reproducibility and enable large data set analysis., This article is based upon work from COST Action StableNextSol MP1307 supported by COST (European Cooperation in Science and Technology). M.V.K., E.A.K., V.B. and A.O. thank the financial support of the United States – Israel Binational Science Foundation (grant no. 2015757). E.A.K., A.A. and I.V.-F. acknowledge partial support from the SNaPSHoTs project in the framework of the German-Israeli bilateral R&D cooperation in the field of applied nanotechnology. M.S.L. thanks the financial support of National Science Foundation (ECCS, award #1610833). S.C., M.Manceau and M.Matheron thank the financial support of European Union’s Horizon 2020 research and innovation programme under grant agreement no 763989 (APOLO project). F.D.R. and T.M.W. would like to acknowledge the support from the Engineering and Physical Sciences Research Council (EPSRC) through the SPECIFIC Innovation and Knowledge Centre (EP/N020863/1) and express their gratitude to the Welsh Government for their support of the Ser Solar programme. P.A.T. acknowledges financial support from the Russian Science Foundation (project No. 19-73-30020). J.K. acknowledges the support by the Solar Photovoltaic Academic Research Consortium II (SPARC II) project, gratefully funded by WEFO. M.K.N. acknowledges financial support from Innosuisse project 25590.1 PFNM-NM, Solaronix, Aubonne, Switzerland. C.-Q.M. would like to acknowledge The Bureau of International Cooperation of Chinese Academy of Sciences for the support of ISOS11 and the Ministry of Science and Technology of China for the financial support (no. 2016YFA0200700). N.G.P. acknowledges financial support from the National Research Foundation of Korea (NRF) grants funded by the Ministry of Science, ICT Future Planning (MSIP) of Korea under contracts NRF-2012M3A6A7054861 and NRF-2014M3A6A7060583 (Global Frontier R&D Program on Center for Multiscale Energy System). CSIRO’s contribution to this work was conducted with funding support from the Australian Renewable Energy Agency (ARENA) through its Advancing Renewables Program. A.F.N gratefully acknowledges support from FAPESP (Grant 2017/11986-5) and Shell and the strategic importance of the support given by ANP (Brazil’s National Oil, Natural Gas and Biofuels Agency) through the R&D levy regulation. Y.-L.L. and Q.B. acknowledge support from the National Science Foundation Division of Civil, Mechanical and Manufacturing Innovation under award no. 1824674. S.D.S. acknowledges the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (HYPERION, grant agreement no. 756962), and the Royal Society and Tata Group (UF150033). The work at the National Renewable Energy Laboratory was supported by the US Department of Energy (DOE) under contract DE-AC36-08GO28308 with Alliance for Sustainable Energy LLC, the manager and operator of the National Renewable Energy Laboratory. The authors (J.J.B, J.M.L., M.O.R, K.Z.) acknowledge support from the ‘De-risking halide perovskite solar cells’ program of the National Center for Photovoltaics, funded by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Solar Energy Technology Office. The views expressed in the article do not necessarily represent the views of the DOE or the US Government. H.J.S. acknowledges the support of EPSRC UK, Engineering and Physical Sciences Research Council. V.T. and M.Madsen acknowledge ‘Villum Foundation’ for funding of the project CompliantPV, under project no. 13365. M.Madsen acknowledges Danmarks Frie Forskningsfond, DFF FTP for funding of the project React-PV, no. 8022-00389B. M.G. and S.M.Z. thank the King Abdulaziz City for Science and technology (KACST) for financial support. S.V. acknowledges TKI-UE/Ministry of Economic Affairs for financial support of the TKI-UE toeslag project POP-ART (no. 1621103). RC thanks the grants for Development of New Faculty Staff, Ratchadaphiseksomphot Endowment Fund. A.D.C. gratefully acknowledges funding from the European Union’s Horizon 2020 Research and Innovation Program (grant agreement no. 785219-GrapheneCore2 and no. 764047-ESPResSo). M.L.C. and H.X. acknowledges the support from Spanish MINECO for the grant GraPErOs (ENE2016-79282-C5-2-R), the OrgEnergy Excellence Network CTQ2016-81911- REDT, the Agència de Gestiód’Ajuts Universitaris i de Recerca (AGAUR) for the support to the consolidated Catalonia research group 2017 SGR 329 and the Xarxa de Referència en Materials Avançats per a l’Energia (Xarmae). ICN2 is supported by the Severo Ochoa program from Spanish MINECO (Grant no. SEV-2017-0706) and is funded by the CERCA Programme/Generalitat de Catalunya.

We demonstrate a novel, simple and low-cost exfoliation technique for large-scale production of graphene nanoplatelets (GNPs) directly from natural pristine graphite using high-pressure airless spray. These GNPs were utilized as a back cathode (counter electrode) in dye-sensitized solar cells (DSSCs). Structural analysis of these GNPs was investigated by X-ray diffraction studies and Raman spectroscopy. Cyclic voltammetry (CV) readings indicated that electro-catalytic behavior for triiodide reduction is comparable to that of Pt electrodes. The photo-conversion efficiency DSSCs fabricated using GNPs based counter electrode is found to be 6.72% under standard illumination (1 sun, 100 mW cm(-2), AM 1.5). The GNPs based counter electrode exhibits good stability over 3000 h under constant illumination with no significant efficiency drop. It is found that the DSSCs fabricated with GNPs based CE shows improved performance in efficiency as compared to other reports where graphene produced by various methods and is used as CE materials. (C) 2018 Elsevier Ltd. All rights reserved.

The accurate and reproducible large-scale production of catalyst layers containing low-cost, abundant electrocatalysts gains in importance. Herein, pivotal factors are discussed that need to be considered when a combined inkjet printing and photonic curing platform is used as a promising fabrication method for catalyst layers based on a model low-cost catalyst, i.e., nitrogen-doped reduced graphene oxide supported cobalt oxide nano sheets (Co3O4/N-rGO), specifically prepared to formulate an inkjet ink. The ink is stable for weeks and can reproducibly be printed with piezoelectric printheads. Ink composition and printing parameters are optimized to achieve high-resolution printing and good adhesion on glassy carbon substrates. Polyvinylpyrrolidone and ethyl cellulose are used as catalyst stabilizers in the ink and must be removed through thermal post-processing to avoid a decrease of the electrical conductivity of the catalyst layer and a degradation of the catalytic activity of the Co3O4 nanocrystals. Conventional slow oven curing (i.e., hours) and photonic curing with a Xe flash lamp (seconds) are compared to generate temperatures above 400 °C under ambient conditions. Both techniques can increase the size of the Co3O4 nanocrystals from ∼7 nm up to ∼15 nm. Photonic curing with pulses above 2 J·cm–2 shot energy density initiates the reduction of the oxidation states of cobalt from (II,III) to (II). Residues and side products of polymeric stabilizers can be found using photonic curing pulses below 10 J·cm–2. This work highlights the advances made in digital printing and post-processing for catalyst layer production and demonstrates the importance of proper design of the ink, the printing and the post-processing for the large-scale production of catalyst layers for the ORR based on low-cost materials. The findings can be transferred to other metal and mixed metal oxide nanocatalysts.

International audience; Partially biobased poly(1,2,3-triazolium)s are synthesized by reversible additionfragmentation chain transfer (RAFT) polymerization of tailor-made 1,2,3-triazole-functionalized (meth)acrylate monomers derived from levulinic acid, followed by N-alkylation of the 1,2,3-triazole moieties by methyl iodide (CH3I) and subsequent anion exchange with lithium bis(trifluoromethylsulfonyl)imide (LiTFSI). Chain extension of a 1,2,3-triazole-functionalized polymethacrylate by RAFT polymerization of styrene followed by N-alkylation with CH3I and anion exchange with LiTFSI affords two poly(1,2,3-triazole)- and two poly(1,2,3-triazolium)-based diblock copolymers (BCPs) with different weight fractions of each block. Discussion of the structure/properties relationships of all obtained materials is based on NMR spectroscopy, size exclusion chromatography, differential scanning calorimetry, thermogravimetric analysis, and broadband dielectric spectroscopy. The morphological and self-assembling properties of neutral and charged BCPs in bulk and in thin films are investigated by small-angle X-ray scattering and atomic force microscopy experiments, respectively.

Truxene (10,15-dihydro-5H-diindeno[ 1,2-a; 1', 2'-c] fluorene) derived blue emitting materials were designed and developed utilizing Suzuki and Buchwald-Hartwig type cross-coupling reactions. The target molecules T-1, T-2 and T-3 bearing N-carbazolyl, 1-pyrenyl and N-phenyl-N-(pyren-1-yl) substituents, respectively at 2,7,12-positions, were synthesized under mild conditions by palladium-catalyzed reactions in good yields. To improve the solution processability of the material, n-hexyl chains were used as substituents at 5,5'-, 10,10'-, 15,15'-positions. From UV-vis measurements, the absorption maxima were found to be at 330 nm for T-1, 356 nm for T-2 and 412 nm for T-3. The materials were found to be blue emitting with their emission maxima at 385 nm, 425 nm and 490 nm for T-1, T-2 and T-3, respectively. The excited state lifetimes were investigated using time correlated single photon counting and were found to be 10 ns, 1.4 ns and 5.4 ns for T-1, T-2 and T-3, respectively. The highest photoluminescence quantum yield was observed in the case of T-2 corresponding to a value of 0.97. The compounds T-2 and T-3 were used as active materials for the fabrication of solution processed, single layer blue light emitting diodes, with low turn-on voltage (2-3.3 V) and Commission Internationale de l'eclairage (CIE) coordinates corresponding to (0.16, 0.23) and (0.17, 0.36) for T-2 and T-3, respectively.

A modified spray pyrolysis technique was employed for the deposition of Cu2CoSnS4 (CCTS) thin films. X-ray diffraction study showed that the CCTS thin films exhibit stannite structure with preferred orientation along (112) plane. The phase purity of sprayed CCTS films was confirmed from Raman analysis, as the most intense peak is observed at 320 cm(-1) corresponding to A1 mode. With increase in substrate temperature the grains over the surface of the CCTS films become more distinct. The EDAX spectrum revealed the presence of different constituent elements such as, Cu, Co, Sn and S for the films deposited at 325 A degrees C. The optical absorption study showed that the energy band gap values of the CCTS films are decreasing from 1.70 to 1.46 eV with respect to increase in substrate temperature from 275 to 325 A degrees C.

For lowering sheet resistance of the TCO, metal fingers are commonly deposited over TCO by methods like vapor deposition, screen printing. The present study reports development of copper current collecting fingers over TCO substrates, involving no high temperature processing step, through electrodeposition. The copper current collecting fingers showed excellent adhesion to the substrate and resulted in improvement in performance over cells prepared on TCO substrate without the fingers owing to decrease in the series resistance in the former case.

An optically transparent and UV-light active anode, characterized by high (photo) conductivity, charge mobility and exciton lifetime, based on graphene, grown by CVD, decorated with colloidal TiO2 nanocrystals (NCs), has been fabricated, by a direct and facile solution-based procedure. TiO2 NCs anchor onto graphene by means of p-p stacking interactions occurring between the pyrene-1-butyric acid (PBA) surface coating ligand and the 2-D platform and assemble in a highly interconnected multilayered layout, by means of interligand pi-pi forces, retaining composition and geometry, along with the graphene structure. Remarkably, the PBA-coated TiO2 NCs on the graphene increase its electrical conductivity, electroactivity, and capacitive behavior, as well as photoelectrical response under UV-light, resulting in a 50% enhanced photoelectroactivity and a long exciton recombination lifetime. The photoanodes can be integrated into solar cells as optically transparent electrodes, in photodetectors, FETs and (bio)sensors.

TiO2 in the form of nanocrystals possesses photocatalyst properties leading to excellent capability of degrading a number of environmental contaminants such as organics, bacteria, and viruses. However, the antimicrobial activity of nano-TiO2 coatings against different microorganisms is not yet well established. Candida albicans, Aspergillus niger, Staphylococcus aureus and Streptococcus mutans are common nosocomial and environmental pathogens responsible for biofilm-associated infections especially in indoor environments. In this study, we produced thin coatings of TiO2 nanoparticles on aluminum substrates and assessed whether they may prevent fungi and bacteria biofilm formation and whether this may be a synergistic effect of TiO2 nanoparticles with UV irradiation, which is more representative of the natural conditions for passive devices. Coatings of flame-synthesized nanoparticles were produced by direct thermophoretic deposition on aluminum substrates through a rotating disk inserted in the flame. Particle and coating characterization was performed by means of differential mobility analysis, Raman and X-ray diffraction spectroscopy. Microbial biofilm formation on substrates with different TiO2 thicknesses were evaluated by the colorimetric crystal violet method and quantified by spectrophotometry in four different fungi and bacteria strains; the results were corroborated by scanning electron microscopy analysis. Substrates with minimal TiO2 nanoparticle layers demonstrated a strong anti-biofilm effect against both fungi and bacteria, due to the well-known cellular component photo-oxidation and to the enhanced nanomaterial surface area. Interestingly, UV irradiation of the substrates at a low intensity for a short time demonstrated a significant enhancement of the titania antimicrobial activity. TiO2 nanoparticle coatings may be proposed as self-cleaning and self-disinfecting materials able to reduce microbial infections, especially in indoor environments where hygiene is needed.

In this account, we discuss the common molecular features and the related chemistry concepts across several different areas of organic electronics, including molecular semiconductors and single-molecule junctions. Despite seemingly diverse charge transport mechanisms and device set-ups, various molecular electronics systems can benefit from the same fundamental principles of physical organic chemistry, based upon the electronic structure and geometry of their molecular building blocks and the intermolecular interactions between them. This is not an exhaustive review of organic electronics, but rather a focused account of primarily our own recent efforts aimed at developing a unified approach to understanding and designing conductive molecular species for diverse electronic applications.

Desirable components for dye-sensitzed solar cell ( DSC) sensitizers and fluorescent imaging dyes include strong donating building blocks coupled with well-balanced acceptor functionalities for absorption beyond the visible range. We have evaluated the effects of increasing acceptor strengths and incorporation of dye morphology controlling groups on molar absorptivity and absorption breadth with indolizine donor-based dyes. Indolizine-based D-A and D-pi-A sensitizers incorporating bis-rhodanine, tricyanofuran ( TCF), and cyanoacrylic acid functionalities were analyzed for performance in DSC devices. The TCF derivatives were also evaluated as near-infrared ( NIR)-emissive materials with the AH25 emissions extending past 1000 nm.

The paper reports the fabrication of Zn-doped TiO2 nanotubes (Zn-TONT)/ZnO nanoflakes heterostructure for the first time, which shows improved performance as a photoanode in dye-sensitized solar cell (DSSC). The layered structure of this novel nanoporous structure has been analyzed unambiguously by Rutherford backscattering spectroscopy, scanning electron microscopy, and X-ray diffractometer. The cell using the heterostructure as photoanode manifests an enhancement of about an order in the magnitude of the short circuit current and a seven-fold increase in efficiency, over pure TiO2 photoanodes. Characterizations further reveal that the Zn-TONT is preferentially oriented in [001] direction and there is a Ti metal-depleted interface layer which leads to better band alignment in DSSC.

We show that charge recombination in ordered heterojunctions depends sensitively on the degree of coherent delocalization of charges at the donor acceptor interface. Depending on the relative sign of the electron and hole transfer integrals, such delocalization can dramatically suppress recombination through destructive quantum interference. This could explain why measured recombination rates are significantly lower than predictions based on Langevin theory for a variety of organic bulk heterojunctions. Moreover, it opens up a design strategy for photovoltaic devices with enhanced efficiencies through coherently suppressed charge recombination.

Cleaning of the FTO substrate is being done to remove the debris present on the substrate during the fabrication of dye sensitized solar cells (DSSC's). Sonication of FTO substrates by keeping it in soap solution, ethanol and distilled water followed by drying at 100 degrees C has been reported by researchers. Some researchers have mentioned the use of ultr aviolet ozonization (UV-O-3) processes to remove the organic contamination over FTO substrates. The present work shows the effect of cleaning of the FTO substrates on efficiency of the DSSC. Cleaning of FTOs was done by two methods - one by only bath sonication and other by bath sonication followed by heat treatment. It was found that heat treatment effectively removed organics compared to the non heat treated process. Heat treatment improved the performance of DSSC's by enhancing the adhesion of titania film to the FTO substrate.

The photoelectrochemical properties and stability of dye sensitized solar cells containing Mn(beta-diketonato)(3) complexes, [Mn-III(acac)(3)] (1) (acac = acetylacetonate), [Mn-III(CF2)(3)] (2) (CF2 = 4,4-difluoro-1-phenylbutanate-1,3-dione), (Mn-III(DBM)(3)] (3) (DBM = dibenzoylmethanate), [Mn-II(CF2)(3)]TBA (TBA = tetrabutylammonium) (4) and [Mn-II(DBM)(3)]TBA (5), have been evaluated. At room temperature, the complexes undergo ligand exchange with 4-tert-butyl-pyridine, an additive commonly used in the solar device to reduce charge recombination at the photoanode. An increased device stability was achieved by using the Z907 dye and passivating the photoanode with short chain siloxanes. It was also found that the Mn(II)/(III) couple is involved in the dye regeneration process, instead of Mn(III)/(IV) (E-1/2 > 1 V vs. SCE) previously indicated in the literature.

This work describes the processability of insoluble or partially soluble polymers based on 3,4-alkylenedioxythiophene (ADOT). Functional and structural variants of poly(3,4-alkylenedioxythiophene) (PADOTs), P1(a-e), are synthesized, in which the side chain bulkiness was minimized to obtain better planarity and strong pi-interaction. P1(a-e) were synthesized via chemical coupling polymerization using palladium acetate as the catalyst. Subsequent polymers structures (P1a to P1e) were obtained with either an enhanced alkylenedioxy bridge and or a side chain substituent in the alternate repeating units. Polymers P1(a-c) are insoluble in all common organic solvents, whereas the hydroxyl functional polymers P1(d-e) are soluble in organic polar solvents, which absorb at 535 nm and display optical properties both in solution and solid state. The conductivity of the oxidized thin films of the soluble polymers P1d and P1e is 4.7 S cm(-1) and 1.5 S cm(-1), respectively. The neutral P1(a-e) polymers were dispersed in aqueous media using polystyrenesulfonate (PSS) and oxidized with sodium persulfate (Na2S2O8). The particle size, stability and ion contents of these aqueous dispersions were characterized via various spectroscopic techniques. The thin films of the P1(a-e): PSS dispersions were transparent with conductivity ranging from 8.1 x 10(-2) to 1.2 x 10(-2) S cm(-1). Spectroelectrochemical studies show that the P1(a-e): PSS polymer films switch between opaque blue to a transmissive oxidized state with optical contrast in the range of 40-46%.

This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited., Incorporation of gold nanoparticles (AuNPs) into titanium dioxide (TiO2) photoelectrodes has been used traditionally to increase the performance of photoelectrochemical cells (PECs) through their tailored optical properties. In contrast to larger AuNPs, previous studies have suggested that smaller AuNPs are the most catalytic or effective at increasing the photovoltaic (PV) performance of TiO2 photoelectrodes based on PECs. Despite this, AuNPs are often only compared between sizes of 12–300 nm in diameter due to the most common synthesis, the Turkevich method, being best controlled in this region. However, the optimum radius for citrate-capped AuNPs sized between 5 and 12 nm, and their influence on the PV performances has not yet been investigated. In addition to using AuNPs in the photoelectrodes, replacing traditional TiO2 NPs with one-dimensional nanofibers (NFs) is a promising strategy to enhance the PV efficiency of the PECs due their capability to provide a direct pathway for charge transport. Herein, we exploit the advantages of two different nanostructured materials, TiO2 NFs and sub-12 nm AuNPs (5, 8, 10, and 12 nm), and fabricate composite based photoelectrodes to conduct a size dependent performance evaluation. The PECs assembled with 8 nm AuNPs showed ∼20% improvement in the average power conversion efficiency compared to the control PECs without AuNPs. The highest performing PEC achieved a power conversion efficiency of 8%, which to the best of our knowledge, is among the highest reported for scattering layers based on pure anatase TiO2 NFs. On the basis of our comprehensive investigations, we attribute this enhanced device performance using 8 nm AuNPs in the TiO2 NF photoelectrodes to the improved spectral absorption, decreased series resistance, and an increase in electron transport and injection rate leading to an increase in current density and fill factor., TJM would like to thank the Ramsay Memorial Trust for their financial assistance. T.J.M and I.P.P would like to acknowledge the EPSRC for financial support (EP/M015157/1).

Organometallic precursors provide a new and clean route to solutions of 2D materials relevant for applications including catalysis, electronics and sensing., 2D inorganic materials and their exfoliated counterparts are both of fundamental interest and relevant for applications including catalysis, electronics and sensing. Here, a new bottom-up synthesis route is used to prepare functionalised nanoplatelets, in apolar organic solvents, via the hydrolysis of organometallic reagents; the products can be prepared in high yield, at room temperature. In particular, a series of layered zinc hydroxides, coordinated by aliphatic carboxylate ligands, were produced by the hydrolysis of diethyl zinc and zinc carboxylate mixtures, optimally at a molar ratio of [COOR]/[Zn] = 0.6. Layered zinc hydroxides coordinated by oleate ligands form high concentration solutions of isolated monolayers (3 nm thick x ∼ 26 nm) in apolar organic solvents (up to 23 mg mL–1 in toluene), as confirmed by both atomic force and transmission electron microscopies of deposited species. The high solubility of the product allows the synthetic pathway to be monitored directly in situ through 1H NMR spectroscopy. The high solubility also provides a route to solution deposition of active functional materials, as illustrated by the formation of nanoporous films of optically transparent porous zinc oxide (1 μm thickness) after annealing at 500 °C. This new organometallic route to 2D materials obviates common complications of top-down exfoliation syntheses, including sonochemical-degradation and low yields of aggregated polydispersed layers, and may potentially be extended to a wide range of systems.

Cs2SnI6 is an air-stable and non-toxic perovskite variant photovoltaic material which exhibits p-type conductivity under doped conditions. In this work, we report the synthesis and stability studies of Cs2SnI6 towards its application as a solid-state Hole Transport Material (HTM) in Titania Nanotube (TNT) based Dye Sensitized Solar Cells (DSSCs). Cs2SnI6 crystals were synthesized using precipitation method and its stability was assessed using X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Thermogravimetric Analysis (TGA). Cs2SnI6 doped with SnI2 was deposited onto the TNT photo-anode as the HTM layer through dip coating. Deposition time was varied to obtain a continuous layer of Cs2SnI6 HTM over TNT photo-anode and cell characteristics were studied. We were able to fabricate air stable, all solid-state solar cells with a Jsc of 6 mA/cm(2), Voc of 536 mV and PCE of 1.3%. The study propounds contemporary analysis on Sn based perovskite systems, in the field of DSSCs.

Titania mesoporous film is a key component of dye-sensitized solar cells (DSSCs) as it transfers electrons from dye molecule to external circuit through the transparent conducting oxide (TCO). Interparticle connectivity, porosity and cracks in the titania films play an important role in determining the performance of DSSCs. The heating schedule with respect to the repetitive coating to build up titania film thickness impacts the titania film characteristics. In the present study, experiments were designed to carry out heat treatments with expectation of improving connectivity and healing cracks. Repetitive screen printing was carried out with either heat treatment after each print step (multiple sintering) or the heat treatment was carried out just once after the desired thickness had been attained (single-step sintering). Interconnectivity of the titania particles in the sintered titania film was analyzed by impedance spectroscopy and nanoindentation. Titania films sintered by MS showed better performance in terms of higher efficiency for the corresponding DSSCs than those prepared using titania films sintered by SS.

FTO and platinum free steel counter electrode substrate based dye-sensitized solar cells (DSSC) are fabricated with few layers graphene (FLG) composite conductive inks. FLG are synthesized by liquid phase high shear exfoliation and the FLG based composite conducting inks are formulated with multi walled carbon nanotubes (MWCNT) and carbon black (CB) in polyimide matrix. The developed ink formulations are suitable for high temperature processing at 500 °C which enables to form graphene based composite conducting films on steel. Polyamic acid (PAA) intermediate layer provides superior adherence and potentio-dynamic polarization studies suggest that PAA coating also provides barrier layer and passivates the corrosion rate. Dye sensitized solar cells have been fabricated with these graphene composite coated on steel substrates which serves as the back electrodes. The cyclic voltammetry (CV) results of FLG composite conductive ink coated steel shows encouraging catalytic activity for the redox reaction of I−/I3− redox mediator. The developed FLG based composite ink formulations and fabrication of working DSSCs with conducting graphene composite coated steel substrate can be a potential step towards the realization of Pt free large area roof top DSSCs.

There has been an increasing interest in plasmon-induced enhancement of solar cells and more recently in the direct generation of photocurrent using noble metal nanoparticles with their Localised Surface Plasmon Resonance (LSPR) in the visual part of the spectrum. In this paper we report broadband plasmon photocurrent generation using novel Au nanoparticle incorporated mesoporous TiO2 nanotube electrodes. Plasmonic induced photocurrent due to hot electrons is observed over a broad wavelength range (~500 to 1000 nm). Incident photon-to-electron conversion efficiency (IPCE) measurements undertaken showed a maximum photocurrent enhancement of 200 fold around 700–730 nm wavelength.

We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.

Titanium dioxide coatings have potential applications including photocatalysts for solar assisted hydrogen production, solar water disinfection and self-cleaning windows. Herein, we report the use of suspension plasma spraying (SPS) for the deposition of conformal titanium dioxide coatings. The process utilises a nanoparticle slurry of TiO2 (ca. 6 and 12 nm respectively) in water, which is fed into a high temperature plasma jet (ca. 7000-20 000 K). This facilitated the deposition of adherent coatings of nanostructured titanium dioxide with predominantly anatase crystal structure. In this study, suspensions of nano-titanium dioxide, made via continuous hydrothermal flow synthesis (CHFS), were used directly as a feedstock for the SPS process. Coatings were produced by varying the feedstock crystallite size, spray distance and plasma conditions. The coatings produced exhibited ca. 90-100% anatase phase content with the remainder being rutile (demonstrated by XRD). Phase distribution was homogenous throughout the coatings as determined by micro-Raman spectroscopy. The coatings had a granular surface, with a high specific surface area and consisted of densely packed agglomerates interspersed with some melted material. All of the coatings were shown to be photoactive by means of a sacrificial hydrogen evolution test under UV radiation and compared favourably with reported values for CVD coatings and compressed discs of P25.

Magnetic and spectroscopic properties of a number of formally antiaromatic carbaporphyrins, carbathiaporphyrins and isophlorins with 4n pi electrons have been investigated at density functional theory and ab initio levels of theory. The calculations show that the paratropic contribution to the magnetically induced ring-current strength susceptibility and the magnetic dipole-transition moment between the ground and the lowest excited state are related. The vertical excitation energy (VEE) of the first excited state decreases with increasing ring-current strength susceptibility, whereas the VEE of the studied higher-lying excited states are almost independent of the size of the ring-current strength susceptibility. Strong antiaromatic porphyrinoids, based on the magnitude of the paratropic ring-current strength susceptibility, have small energy gaps between the highest occupied and lowest unoccupied molecular orbitals and a small VEE of the first excited state. The calculations show that only the lowest S-0 -> S-1 transition contributes signficantly to the magnetically induced ring-current strength susceptibility of the antiaromatic porphyrinoids. The decreasing optical gap combined with a large angular momentum contribution to the magnetic transition moment from the first excited state explains why molecules III-VII are antiaromatic with very strong paratropic ring-current strength susceptibilities. The S-0 -> S-1 transition is a magnetic dipole-allowed electronic transition that is typical for antiaromatic porphyrinoids with 4n pi electrons.