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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

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.

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.

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.

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.

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.

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.

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.

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.

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%.

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.

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.

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.

We report on the synthesis, characterization, and optoelectronic properties of the novel trimethylsulfonium lead triiodide perovskite, (CH3)3SPbI3. At room temperature, the air-stable compound adopts a hexagonal crystal structure with a 1D network of face-sharing [PbI6] octahedra along the c axis. UV–vis reflectance spectroscopy on a pressed pellet revealed a band gap of 3.1 eV, in agreement with first-principles calculations, which show a small separation between direct and indirect band gaps. Electrical resistivity measurements on single crystals indicated that the compound behaves as a semiconductor. According to multi-temperature single-crystal X-ray diffraction, synchrotron powder X-ray diffraction, Raman spectroscopy, and differential scanning calorimetry, two fully reversible structural phase transitions occur at −5 and ca. −100 °C with reduction of the unit cell symmetry to monoclinic as temperature decreases. The role of the trimethylsulfonium cation regarding the chemical stability and optoelect...

Experimental data for the density, viscosity, refractive index, and surface tension of four sulfonium- and ammonium-based ionic liquids (ILs) with the common bis(trifluoromethylsulfonyl)imide anion were measured in the temperature range between 288.15 and 353.15K and at atmospheric pressure. The ILs considered include butyltrimethylammonium bis(trifluoromethylsulfonyl)imide, [N-4111][NTf2], tributyl-methylammonium bis(trifluoromethylsulfonyl)imide, [N-4441][NTf2], diethylmethylsulfonium bis(trifluoromethylsulfonyl)imide, [S-221] [NTf2], and triethylsulfonium bis(trifluoromethylsulfonyl)imide, [S-222][NTf2]. Based on the gathered results and on data taken from literature, the impact of the cation isomerism and of the size of the aliphatic tails, as well as the effect resulting from the substitution of a nitrogen by a sulfur atom as the cation central atom, on the thermophysical properties of sulfonium- and ammonium-based Its is discussed here. Remarkably, more symmetric cations present a lower viscosity for the same, and sometimes even for higher, alkyl chain lengths at the cation. Additional derivative properties, such as the isobaric thermal expansion coefficient, the surface thermodynamic properties and the critical temperature for the investigated ILs were also estimated and are presented and discussed. (C) 2014 Elsevier B.V. All rights reserved.

Conductivity enhancement of thin transparent films based on poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) by a solution-processed route involving mixture of an organic acid and organic solvent is reported. The combined effect of p-toluenesulfonic acid and dimethyl sulfoxide on spin-coated films of PEDOT-PSS on glass substrates, prepared from its commercially available aqueous dispersion, was found to increase the conductivity of the PEDOT-PSS film to similar to 3500 S.cm(-1) with a high transparency of at least 94%. Apart from conductivity and transparency measurements, the films were characterized by Raman, infrared, and X-ray photoelectron spectroscopy along with atomic force microscopy and secondary ion mass spectrometry. Combined results showed that the conductivity enhancement was due to doping, rearrangement of PEDOT particles owing to phase separation, and removal of PSS matrix throughout the depth of the film. The temperature dependence of the resistance for the treated films was found to be in accordance with one-dimensional variable range hopping, showing that treatment is effective in reducing energy barrier for interchain and interdomain charge hopping. Moreover, the treatment was found to be compatible with flexible poly(ethylene terephthalate) (PET) substrates as well. Apart from being potential candidates to replace inorganic transparent conducting oxide materials, the films exhibited stand-alone catalytic activity toward I-/I-3(-) redox couple as well and successfully replaced platinum and fluorinated tin oxide as counter electrode in dye-sensitized solar cells.

A Wittig reaction was employed to synthesize conjugated BODIPYs in high yields by treating formylated BODIPYs with alkyl/aryl ylides under simple room temperature conditions. Treatment of 3,5-diformyl BODIPYs or a-formyl 3-pyrrolyl BODIPY with different alkyl/aryl ylides in CH2Cl2 at room temperature for 2 h followed by straightforward column chromatographic purification on silica afforded conjugated BODIPYs in similar to 65-90% yields. This is an alternate method to Knoevenagel and Heck reactions which have been used to synthesize such conjugated BODIPYs. The method works very efficiently, and we prepared 12 substituted BODIPYs including cholesterol-substituted BODIPYs to demonstrate the versatility of the reaction. The spectral, electrochemical, and fluorescence properties of these conjugated BODIPYs are also described.

Metal oxides are versatile substrates for the design of a wide range of SAM-based organic-inorganic materials among which ZnO nanostructures modified with phosphonic SAM are promising semiconducting systems for applications in technological fields such as biosensing, photonics, and field-effect transistors (FET). Despite previous studies reported on various successful grafting approaches, issues regarding preferred anchoring modes of phosphonic acids and the role of a second reactive group (i.e., a carboxylic group) are still a matter of controversial interpretations. This paper reports on an experimental and theoretical study on the functionalization of ZnO nanorods with monofunctional alkylphosphonic and bifunctional carboxyalkylphosphonic acids. X-ray photoelectron and infrared spectroscopies have been combined with DFT modeling to explain and understand the interactions that drive the surface anchoring of phosphonic acids on ZnO surface. It was found that both monofunctional and bifunctional acids anchor on ZnO through a multidentate bonding which involves both P=O and P-O moieties of the phosphonic group. Moreover, anchored bifunctional acids bend to the surface, promoting a further interaction between surface hydroxyl groups and carboxylic terminations. This secondary interaction can be limited by increasing the surface density of the anchored molecules.

Dye-sensitized solar cells (DSSCs) have attracted significant interest in the last few years as effective low-cost devices for solar energy conversion. We have analyzed the excited state dynamics of several organic dyes bearing both cyanoacrylic acid and siloxane anchoring groups. The spectroscopic properties of the dyes have been studied both in solution and when adsorbed on a TiO2 film using stationary and time-resolved techniques, probing the sub-picosecond to nanosecond time interval. The comparison between the spectra registered in solution and on the solid substrate evidences different pathways for energy and electron relaxation. The transient spectra of the TiO2-adsorbed dyes show the appearance of a long wavelength excited state absorption band, attributed to the cationic dye species, which is absent in the spectra measured in solution. Furthermore, the kinetic traces of the samples adsorbed on the TiO2 film show a long decay component not present in solution which constitutes indirect evidence of electron transfer between the dye and the semiconductor. The interpretation of the experimental results has been supported by theoretical DFT calculations of the excited state energies and by the analysis of molecular orbitals of the analyzed dye molecules.

International audience; Metal ions are frequently incorporated into crystalline materials to improve their electrochemical properties and to confer new physicochemical properties. Naturally-occurring phosphate apatite, which is formed geologically and in biomineralization processes, has extensive potential applications and is therefore an attractive functional material. In this study, we generate a novel building block for flexible optoelectronics using bio-inspired methods to deposit a layer of photoactive titanium-modified hydroxyapatite (TiHA) nanoparticles (NPs) on conductive polypyrrole(PPy)-coated wool yarns. The titanium concentration in the reaction solution was varied between 8–50 mol% with respect to the phosphorous, which led to titanate ions replacing phosphate in the hydroxyapatite lattice at levels up to 17 mol%. PPy was separately deposited on wool yarns by oxidative polymerization, using two dopants: (i) anthraquinone-2,6-disulfonic acid to increase the conductivity of the PPy layer and (ii) pyroglutamic acid, to reduce the resistivity of the wool yarns and to promote the heterogeneous nucleation of the TiHA NPs. A specific titanium concentration (25 mol% wrt P) was used to endow the TiHA NPs on the PPy-coated fibers with a desirable band gap value of 3.68 eV, and a specific surface area of 146 m2 g−1. This is the first time that a thin film of a wide-band gap semiconductor has been deposited on natural fibers to create a fiber-based building block that can be used to manufacture flexible electronic devices.