pinecone/core-2020-05-10-deduplication huggingface dataset:
A High Power-Density Mediator-Free Microfluidic Biophotovoltaic Device for Cyanobacterial Cells

Biophotovoltaics has emerged as a promising technology for generating renewable energy since it relies on living organisms as inexpensive, self-repairing and readily available catalysts to produce electricity from an abundant resource - sunlight. The efficiency of biophotovoltaic cells, however, has remained significantly lower than that achievable through synthetic materials. Here, we devise a platform to harness the large power densities afforded by miniaturised geometries. To this effect, we have developed a soft-lithography approach for the fabrication of microuidic biophotovoltaic devices that do not require membranes or mediators. Synechocystis sp. PCC 6803 cells were injected and allowed to settle on the anode, permitting the physical proximity between cells and electrode required for mediator-free operation. We demonstrate power densities of 100 mW/m^2 for a chlorophyll concentration of above 100 μM under white light, a high value for biophotovoltaic devices without extrinsic supply of additional energy.RCUK, OtherThis is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/aenm.20140129
Energy harvesting technologies for tire pressure monitoring systems

Tire pressure monitoring systems (TPMS) are becoming increasingly important to ensure safe and efficient use of tires in the automotive sector. A typical TPMS system consists of a battery powered wireless sensor, as part of the tire, and a remote receiver to collect sensor data, such as pressure and temperature. In order to provide a maintenance-free and battery-less sensor solution there is growing interest in using energy harvesting technologies to provide power for TPMS. This paper summarizes the current literature and discusses the use of piezoelectric, electromagnetic, electret and triboelectric materials in a variety of harvesting systems
Micropatterning of flexible and free standing polyvinylidene difluoride (PVDF) films for enhanced pyroelectric energy transformation

In an effort to harvest thermal energy and exploit abundantly available waste heat the pyroelectric effect offers the opportunity to convert temperature fluctuations into useable electrical energy. Here, the micropatterning of the surface of a pyroelectric in order to enhance heat transfer and achieve faster and larger temperature fluctuations, which improve pyroelectric energy transformation, is reported. Methods for the fabrication of partially covered electrodes on polyvinylidene difluoride (PVDF) films are developed to investigate and quantify the benefits of such an electrode structure for pyroelectric energy harvesting. The micropattern consists of an array of holes that are etched into the upper aluminum electrodes of free standing ferroelectric PVDF films using a low cost photolithography and wet etching process. Under the application of infrared radiation heating, it is demonstrated that such microfeatures are able to significantly improve the open circuit voltage by 380% and the closed circuit current by 420% for an electrode area coverage of 45% when compared to a fully covered electrode design. Capacitance measurements show constant electric fields with microfeatures for electrode area coverages as low as 28%. A specific generator performance of 66.9 μJ cm−3 cycle−1 is presented at oscillation temperatures of 2.8 °C
Enhancement of Thermoelectric Performance of n-Type PbSe by Cr Doping with Optimized Carrier Concentration

Ti, V, Cr, Nb, and Mo are found to be effective at increasing the Seebeck coefficient and power factor of n-type PbSe at temperatures below 600 K. It is found that the higher Seebeck coefficients and power factors are due to higher Hall mobility ≈1000 cm[superscript 2] V[superscript −]1s[superscript −1] at lower carrier concentration. A larger average ZT value (relevant for applications) can be obtained by an optimization of carrier concentration to ≈10[superscript 18]–10[superscript 19] cm[superscript −3]. Even though the highest room temperature power factor ≈3.3 × 10[superscript −3] W m[superscript −1] K[superscript −2] is found in 1 at% Mo-doped PbSe, the highest ZT is achieved in Cr-doped PbSe. Combined with the lower thermal conductivity, ZT is improved to ≈0.4 at room temperature and peak ZTs of ≈1.0 are observed at ≈573 K for Pb[subscript 0.9925]Cr[subscript 0.0075]Se and ≈673 K for Pb[subscript 0.995]Cr[subscript 0.005]Se. The calculated device efficiency of Pb[subscript 0.995]Cr[subscript 0.005]Se is as high as ≈12.5% with cold side 300 K and hot side 873 K, higher than those of all the n-type PbSe materials reported in the literature.United States. Dept. of Energy. Office of Science (Solid-State Solar-Thermal Energy Conversion Center Award DE-SC0001299
Shelf Life Degradation of Bulk Heterojunction Solar Cells: Intrinsic Evolution of Charge Transfer Complex

Achievement of long-term stability of organic photovoltaics is currently one of the major topics for this technology to reach maturity. Most of the techniques used to reveal degradation pathways are destructive and/or do not allow for real-time measurements in operating devices. Here, three different, nondestructive techniques able to provide real-time information, namely, film absorbance, capacitance–voltage (C–V), and impedance spectroscopy (IS), are combined over a period of 1 year using non-accelerated intrinsic degradation conditions. It is discerned between chemical modifications in the active layer, physical processes taking place in the bulk of the blend from those at the active layer/contact interfaces. In particular, it is observed that during the ageing experiment, the main source for device performance degradation is the formation of donor–acceptor charge-transfer complex (math formula–math formula) that acts as an exciton quencher. Generation of these radical species diminishes photocurrent and reduces open-circuit voltage by the creation of electronic defect states. Conclusions extracted from absorption, C–V, and IS measurements will be further supported by a range of other techniques such as atomic force microscopy, X-ray diffraction, and dark-field imaging of scanning transmission electron microscopy on ultrathin cross-sections.This work was partially supported by the FP7 European collaborative project SUNFLOWER (FP7-ICT-2011–7 Contract No. 287594), and the Generalitat Valenciana (Project No. ISIC/2012/008, Institute of Nanotechnologies for Clean Energies). S.B. acknowledges financial support from the European Research Council (ERC Starting Grant No. 335078-COLOURATOMS). A.K. acknowledges Brno University of Technology for financial support (CZ.1.07/2.3.00/30.0039). M.P. gratefully acknowledges the SIM NanoForce program for their financial support. The authors would like to thank Dr. Beatriz Julián López for her support to carry out the absorption measurements using the integrating sphere
Multi-functional Coatings from Scalable Single Source Precursor Chemistry in Tandem Photoelectrochemical Water Splitting

The straightforward and inexpensive fabrication of stabilized and activated photoelectrodes for application in tandem photoelectrochemical (PEC) water splitting is reported. Semiconductors such as Si, WO3 and BiVO4 can be coated with a composite layer formed upon hydrolytic decomposition of heterobimetallic single source precursors (SSPs) based on Ti and Ni or Ti and Co in a simple single-step process under ambient conditions. The resulting 3d-transition metal oxide composite films are multi-functional, as they protect the semiconductor electrode from corrosion with an amorphous TiO2 coating and act as bifunctional electrocatalysts for H2 and O2 evolution based on catalytic Ni or Co species. Thus, this approach enables the use of the same precursors for both photoelectrodes in tandem PEC water splitting, and SSP chemistry is thereby established as a highly versatile low-cost approach to protect and activate photoelectrodes. In an optimized system, SSP coating of a Si photocathode and a BiVO4 photoanode resulted in a benchmark noble-metal free dualphotoelectrode tandem PEC cell for overall solar water splitting with an applied bias solar-tohydrogen efficiency of 0.59% and a half-life photostability of five hours.Financial support from the Christian Doppler Research Association (Austrian Federal Ministry of Science, Research and Economy and National Foundation for Research, Technology and Development), the OMV Group and the EPSRC (EP/H00338X/2) is gratefully acknowledged. D.W.P. acknowledges support from the Winston Churchill Foundation of the United States. We thank the National EPSRC XPS User’s Service (NEXUS) at Newcastle University, an EPSRC Mid-Range Facility for XPS measurements.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/aenm.20150166
Bi-functional iron-only electrodes for efficient water splitting with enhanced stability through in-situ electrochemical regeneration

Scalable and robust electrocatalysts are required for the implementation of water splitting technologies as a globally applicable means of producing affordable renewable hydrogen. We demonstrate herein that iron-only electrode materials prove to be active for catalyzing both proton reduction and water oxidation in alkaline electrolyte solution with superior activity to that of previously established bi-functional catalysts containing less abundant elements. The reported bi-functionality of the iron electrodes is reversible upon switching of the applied bias through electrochemical interconversion of catalytic species at the electrode surface. Cycling of the applied bias results in in-situ electrochemical regeneration of the catalytic surfaces and thereby extends the catalyst stability and lifetime of the water electrolyzer. Full water splitting at a current density of I = 10 mA cm⁻² is achieved at a bias of approximately 2 V which is stable over at least 3 days (72 one hour switching cycles). Thus, potential-switching is established as a possible strategy of stabilizing electrode materials against degradation in symmetrical water splitting systems.The author’s thank the Oppenheimer Fund (University of Cambridge), the EPSRC (Grant EP/H00338X/2), the Christian Doppler Research Association (Austrian Federal Ministry of Science, Research and Economy and National Foundation for Research, Technology and Development) and OMV Group for financial support. We also thank the National EPSRC XPS User’s Service (NEXUS) at Newcastle University, UK, where XPS spectra were obtained. Dr Chia-Yu Lin is acknowledged for his invaluable help in initial experiments.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/aenm.20150209
Impact of Monovalent Cation Halide Additives on the Structural and Optoelectronic Properties of CH$_{3}$NH$_{3}$PbI$_{3}$ Perovskite

The influence of monovalent cation halide additives on the optical, excitonic, and electrical properties of CH$_{3}$NH$_{3}$PbI$_{3}$ perovskite is reported. Monovalent cation halide with similar ionic radii to Pb$^{2+}$, including Cu$^{+}$, Na$^{+}$, and Ag$^{+}$, have been added to explore the possibility of doping. Significant reduction of sub-bandgap optical absorption and lower energetic disorder along with a shift in the Fermi level of the perovskite in the presence of these cations has been observed. The bulk hole mobility of the additive-based perovskites as estimated using the space charge limited current method exhibits an increase of up to an order of magnitude compared to the pristine perovskites with a significant decrease in the activation energy. Consequentially, enhancement in the photovoltaic parameters of additive-based solar cells is achieved. An increase in open circuit voltage for AgI (≈1.02 vs 0.95 V for the pristine) and photocurrent density for NaI- and CuBr-based solar cells (≈23 vs 21 mA cm$^{−2}$ for the pristine) has been observed. This enhanced photovoltaic performance can be attributed to the formation of uniform and continuous perovskite film, better conversion, and loading of perovskite, as well as the enhancement in the bulk charge transport along with a minimization of disorder, pointing towards possible surface passivation.M.A.J. thanks Nyak Technology Limited for a PhD scholarship. M.I.D., S.M.Z., and M.G. thank the King Abdulaziz City for Science and Technology (KACST) and Swiss National Science Foundation (SNSF) for financial support. N.A. gratefully acknowledges financial support from the Swiss confederation under Swiss Government Scholarship program. The authors would like to thank Dr. Pierre Mettraux in Molecular and Hybrid Materials Characterization Center, EPFL for carrying out XPS measurements. A.S. gratefully acknowledges financial support from the Indo-UK APEX project. S.P.S. acknowledges Royal Scociety London for the Newton Fellowship. R.H.F, M.A.J., and A.S. would like to acknowledge the support from EPSRC.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/aenm.20150247
Oxygen Degradation in Mesoporous Al$_{2}$O$_{3}$/CH$_{3}$NH$_{3}$PbI$_{3-x}$Cl$_{x}$ Perovskite Solar Cells: Kinetics and Mechanisms

The rapid pace of development for hybrid perovskite photovoltaics has recently resulted in promising figures of merit being obtained with regard to device stability. Rather than relying upon expensive barrier materials, realizing market-competitive lifetimes is likely to require the development of intrinsically stable devices, and to this end accelerated aging tests can help identify degradation mechanisms that arise over the long term. Here, oxygen-induced degradation of archetypal perovskite solar cells under operation is observed, even in dry conditions. With prolonged aging, this process ultimately drives decomposition of the perovskite. It is deduced that this is related to charge build-up in the perovskite layer, and it is shown that by efficiently extracting charge this degradation can be mitigated. The results confirm the importance of high charge-extraction efficiency in maximizing the tolerance of perovskite solar cells to oxygen.This work was supported by SABIC and by the EPSRC, including by the Supergen Supersolar Consortium (EP/J017361/1) and the European Union Seventh Framework Program [FP7 2007-2003] under grant agreement 604032 of the MESO project. GE is supported by the EPSRC and Oxford Photovoltaics Ltd. through a Nanotechnology KTN CASE award. JW acknowledges the Swire Educational Trust for supporting his D.Phil. study at Oxford. We thank Sian Dutton (University of Cambridge) for access to XRD facilities and Felix Deschler (University of Cambridge) for helpful discussions.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/aenm.20160001
Interface-engineered all-solid-state Li-ion batteries based on garnet-type fast Li+ conductors

All-solid-state Li-ion batteries based on Li7La3Zr2O12 (LLZO) garnet structures require novel electrode assembly strategies to guarantee a proper Li+ transfer at the electrode–electrolyte interfaces. Here, first stable cell performances are reported for Li-garnet, c-Li6.25Al0.25La3Zr2O12, all-solid-state batteries running safely with a full ceramics setup, exemplified with the anode material Li4Ti5O12. Novel strategies to design an enhanced Li+ transfer at the electrode–electrolyte interface using an interface-engineered all-solid-state battery cell based on a porous garnet electrolyte interface structure, in which the electrode material is intimately embedded, are presented. The results presented here show for the first time that all-solid-state Li-ion batteries with LLZO electrolytes can be reversibly charge–discharge cycled also in the low potential ranges (≈1.5 V) for combinations with a ceramic anode material. Through a model experiment, the interface between the electrode and electrolyte constituents is systematically modified revealing that the interface engineering helps to improve delivered capacities and cycling properties of the all-solid-state Li-ion batteries based on garnet-type cubic LLZO structures.Competence Center Energy and Mobility (CCEM); Alstom; ETH Zurich Foundation (SP-ESC-A03-14
Baselines for lifetime of organic solar cells

The process of accurately gauging lifetime improvements in organic photovoltaics (OPVs) or other similar emerging  technologies, such as perovskites solar cells is still a major challenge. The presented work is part of a larger effort of developing a worldwide database of lifetimes that can help establishing reference baselines of stability performance for OPVs and other emerging PV technologies, which can then be utilized for pass-fail testing standards and predicting tools. The study constitutes scanning of literature articles related to stability data of OPVs, reported until mid-2015
and collecting the reported data into a database. A generic lifetime marker is utilized for rating the stability of various
reported devices. The collected data is combined with an earlier developed and reported database, which was based on
articles reported until mid-2013. The extended database is utilized for establishing the baselines of lifetime for OPVs
tested under different conditions. The work also provides the recent progress in stability of unencapsulated OPVs with
different architectures, as well as presents the updated diagram of the reported record lifetimes of OPVs. The presented
work is another step forward towards the development of pass-fail testing standards and lifetime prediction tools for
emerging PV technologies.This work has been supported by European Commission StableNextSol COST Action MP1307. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 609788 (CHEETAH)
Evidence of enhanced ion transport in Li-rich silicate intercalation materials

Financial support from the EPSRC Supergen Energy Storage Consortium (EP/L019469/1) and the Energy Materials Programme Grant (EP/K016288) is gratefully acknowledgedThe silicate compounds Li2MSiO4 (where M = Mn, Fe, Co) have received significant attention recently as Li intercalation electrodes. Overwhelmingly they exhibit relatively poor kinetics of ion intercalation. By synthesizing Li-rich solid solutions of the form Li2+2xFe1−xSiO4 (with 0 ≤ x ≤ 0.3), the structural requirements for fast ion transport and hence relatively fast intercalation have been identified. Specifically the presence of additional Li+ in interstitial sites, not normally occupied in the stoichiometric Li2FeSiO4 compound, enhances ion transport by more than two orders of magnitude. The results, obtained by combining electrochemical measurements, with powder X-ray and neutron diffraction and atomistic modeling of the ion dynamics, provide valuable guidance in designing future intercalation electrodes with high Li-ion transport and, hence, fast electrode kinetics.Publisher PDFPeer reviewe
Toward High-Temperature Stability of PTB7-Based Bulk Heterojunction Solar Cells: Impact of Fullerene Size and Solvent Additive

The use of fullerene as acceptor limits the thermal stability of organic solar
cells at high temperatures as their diffusion inside the donor leads to phase
separation via Ostwald ripening. Here it is reported that fullerene diffusion is
fully suppressed at temperatures up to 140 °C in bulk heterojunctions based
on the benzodithiophene-based polymer (the poly[[4,8-bis[(2-ethylhexyl)oxy]-
benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]-
thieno[3,4-b]thiophenediyl]], (PTB7) in combination with the fullerene derivative
[6,6]-phenyl-C71-butyric acid methyl ester (PC70BM). The blend stability is
found independently of the presence of diiodooctane (DIO) used to optimize
nanostructuration and in contrast to PTB7 blends using the smaller fullerene
derivative PC70BM. The unprecedented thermal stability of PTB7:PC70BM
layers is addressed to local minima in the mixing enthalpy of the blend
forming stable phases that inhibit fullerene diffusion. Importantly, although
the nanoscale morphology of DIO processed blends is thermally stable, corresponding
devices show strong performance losses under thermal stress.
Only by the use of a high temperature annealing step removing residual DIO
from the device, remarkably stable high efficiency solar cells with performance
losses less than 10% after a continuous annealing at 140 °C over
3 days are obtained. These results pave the way toward high temperature
stable polymer solar cells using fullerene acceptors.The authors acknowledge financial support by the French Fond Unique
Interministériel (FUI) under the project “SFUMATO” (grant number:
F1110019V/201308815) as well as by the European Commission under
the Project “SUNFLOWER” (FP7-ICT-2011-7, grant number: 287594).
Generalitat Valenciana (ISIC/2012/008 Institute of Nanotechnologies for
Clean Energies) is also acknowledged for providing financial support.
The authors further acknowledge financial support via ERC Starting
Grant Colouratoms (335078)
High-Efficiency Perovskite Solar Cells using Molecularly-Engineered, Thiophene-Rich,Hole-Transporting Materials: Influence of Alkyl Chain Length on Power Conversion Efficiency

The synthesis and characterization of a series of novel small-molecule hole-transporting materials (HTMs) based on an anthra[1,2-b:4,3-b′:5,6-b′′:8,7-b′′′]tetrathiophene (ATT) core are reported. The new compounds follow an easy synthetic route and have no need of expensive purification steps. The novel HTMs were tested in perovskite solar cells (PSCs) and power conversion efficiencies (PCE) of up to 18.1 % under 1 sun irradiation were 2 measured. This value is comparable with the 17.8 % efficiency obtained using spiroOMeTAD as a reference compound. Similarly, a significant quenching of the Photoluminescence in the first nanosecond is observed, indicative of effective hole transfer.Additionally, the influence of introducing aliphatic alkyl chains acting as solubilizers on the device performance of the ATT molecules is investigated. Replacing the methoxy groups on the triarylamine sites by butoxy-, hexoxy- or decoxy-substituents greatly improved the solubility of the compounds without changing the energy levels, yet at the same time significantly decreasing the conductivity as well as the PCE, 17.3 % for ATT-OBu, 15.7 % for ATT-OHex and 9.7 % for ATT-ODec
Rutile TiO2 inverse opal anodes for Li-ion batteries with long cycle life, high-rate capability and high structural stability

Rutile TiO2 inverse opals provide long cycle life and impressive structural stability when tested as anode materials for Li-ion batteries. The capacity retention of TiO2 inverse opals (IOs) is greater than previously reported values for other rutile TiO2 nanomaterials, and the cycled crystalline phase and material interconnectivity is maintained over thousands of cycles. Consequently, this paper offers insight into the importance of optimizing the relationship between the structure and morphology on improving electrochemical performance of this abundant and low environmental impact material. TiO2 IOs show gradual capacity fading over 1000 and 5000 cycles, when cycled at specific currents of 75 and 450 mA g−1, respectively, while maintaining a high capacity and a stable overall cell voltage. TiO2 IOs achieve a reversible capacity of ≈170 and 140 mA h g−1 after the 100th and 1000th cycles, respectively, at a specific current of 75 mA g−1, corresponding to a capacity retention of ≈82.4%. The structural stability of the 3D IO phase from pristine rutile TiO2 to the conductive orthorhombic Li0.5TiO2 is remarkable and maintains its structural integrity. Image analysis conclusively shows that volumetric swelling is accommodated into the predefined pore space, and the IO periodicity remains constant and does not degrade over 5000 cycles