pinecone/core-2020-05-10-deduplication huggingface dataset:
Application of metal − organic frameworks

The burgeoning field of metal-organic frameworks or porous coordination polymers has received increasing interest in recent years. In the last decade these microporous materials have found several applications including storage and separation of gases, sensors, catalysis and functional materials. In order to better design new metal-organic frameworks and porous coordination polymers with specific functionalities a fundamental issue is to achieve a basic understanding of the relationship between molecular parameters and structures, preferred adsorption sites and properties by using using modern theoretical methods. The focus of this mini-review is a description of the potential and emerging applications of metal-organic framework
Physico-mechanical properties of nano polystyrene (nPS) decorated graphene oxide (GO) -epoxy composites.

In this work, nano polystyrene (nPS) decorated graphene oxide (GO) hybrid nanostructures were successfully synthesized using stepwise micro emulsion polymerization, and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). XRD and FTIR spectra revealed the existence of a strong interaction between the nPS and GO, which implies that the polymer chains were successfully grafted onto the surface of the GO. The nPS decorated GO hybrid nanostructures were compounded with epoxy by hand lay-up technique, and the effect of the nPS-GO on the mechanical, thermal and surface morphological properties of the epoxy matrix was investigated by Universal tensile machine (UTM), Izod impact tester, thermogravimetric analysis (TGA) and contact angle measurement by a goniometer. It was observed that in the epoxy matrix, GO improved the compatibility.Department of Science and Technology (DST-UKIERI), New Delhi, India File No: DST/INT, UK/P-108/2014 ; University Grant Commission (UGC), New Delhi, Government of India - Rajiv Gandhi National Junior Research Fellowship F1-17.1/2014-15/RGNF-2014-15-SC-MAH-58232/(SA-III/Website)
High performance thermosets with tailored properties derived from methacrylated eugenol and epoxy-based vinyl ester

A renewable chemical, eugenol, is methacrylated to produce methacrylated eugenol (ME) employing the Steglich esterification reaction without any solvent. The resulting ME is used as a low viscosity comonomer to replace styrene in a commercial epoxy-based vinyl ester resin (VE). The volatility and viscosity of ME and styrene are compared. The effect of ME loadings and temperatures on viscosity of the VE-ME resin is investigated. Moreover, the thermo-mechanical properties, curing extent, and thermal stability of the fully cured VE-ME thermosets are systematically examined. The results indicate that ME is a monomer with low volatility and low viscosity, and therefore the incorporation of ME monomer in VE resins allows significant reduction of viscosity. Moreover, viscosity of the VE-ME resin can be tailored by adjusting ME loadings and processing temperature to meet commercial liquid molding technology requirements. The glass transition temperatures of VE-ME thermosets range from 139 to 199 °C. In addition, more than 95% of the monomer is incorporated and fixed in the crosslinked network structure of VE-ME thermosets. Overall, the developed ME monomer exhibits promising potential to replace styrene as an effective low viscosity comonomer. The VE-ME resins show great advantages for use in polymer matrices for high performance fiber-reinforced composites. This work showed great significance to the vinyl ester industry by providing detailed experimental support
Ultrafast near infrared sintering of TiO2 layers on metal substrates for dye-sensitized solar cells

A limiting step to roll-to-roll production of dye-sensitized solar cells on metals is TiO2 sintering (10-30 min). Near infrared (NIR) heating is a novel process innovation which directly heats titanium substrates giving rapid binder removal and sintering. NIR heating (for 12.5 s) at varying power gave titanium temperatures of 545, 685 and 817 degrees Celsius yielding cells with efficiencies of 2.9, 2.8 and 2.5%. Identical cells prepared in a conventional oven (1800 s) at 500, 600 and 800 degrees Celsius gave 2.9, 2.6 and 0.2% efficiency. NIR sintering is ultrafast and has a wide process window making it ideal for rapid manufacturing on metals
Effects of spectrum on the power rating of amorphous silicon photovoltaic devices

This is the peer reviewed version of the following article, which has been published in final form at http://dx.doi.org/10.1002/pip.1080. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.The effects of different spectra on the laboratory based performance evaluation of amorphous silicon solar cells is investigated using an opto-electrical model which was developed specifically for this purpose. The aim is to quantify uncertainties in the calibration process. Two main uncertainties arise from the differences in the test spectrum and the standard spectrum. First, the mismatch between reference cells and the measured device, which is shown to be voltage dependent in the case of amorphous silicon devices. Second, the fill factor of the device is affected by different spectra. Different cell structures and states (specifically different i-layer thickness and levels of degradation) for the different light sources are investigated in this work. These sources are different solar simulators, LED sources, Tungsten as well as the standard terrestrial AM1.5G radiation. It is shown that the performance cannot be evaluated by short circuit current alone. The voltage dependent quantum efficiency of p-i-n devices can introduce a mismatch in the PMPP of 1% for 250nm i-layer devices in as prepared state, rising to up to 4% for the 600nm i-layer devices at degraded state
Impact of phosphorus gettering parameters and initial iron level on silicon solar cell properties

We have studied experimentally the effect of different initial iron contamination levels on the electrical device properties of p-type Czochralski-silicon solar cells. By systematically varying phosphorus diffusion gettering (PDG) parameters, we demonstrate a strong correlation between the open-circuit voltage (Voc) and the gettering efficiency. Similar correlation is also obtained for the short-circuit current (Jsc), but phosphorus dependency somewhat complicates the interpretation: the higher the phosphorus content not only the better the gettering efficiency but also the stronger the emitter recombination. With initial bulk iron concentration as high as 2 × 1014 cm−3, conversion efficiencies comparable with non-contaminated cells were obtained, which demonstrates the enormous potential of PDG. The results also clearly reveal the importance of well-designed PDG: to achieve best results, the gettering parameters used for high purity silicon should be chosen differently as compared with for a material with high impurity content. Finally we discuss the possibility of achieving efficient gettering without deteriorating the emitter performance by combining a selective emitter with a PDG treatment.Peer reviewe
Enhanced performance in the deteriorated area of multicrystalline silicon wafers by internal gettering

The deteriorated area of the multicrystalline silicon (mc-Si) ingots grown by directional solidification, commonly known as the Red Zone, is usually removed before wafering. This area, characterized by poor minority carrier lifetime, is located on the sides, at the top, and the bottom of the mc-Si ingots. In this study, the effect of internal gettering by oxygen precipitates and structural defects has been investigated on the bottom zone of a mc-Si ingot. Nucleation and growth of oxygen precipitates as well as low temperature annealing were studied. Photoluminescence imaging, lifetime mapping, and interstitial iron measurements performed by μ-PCD reveal a considerable reduction of the bottom Red Zone. An improvement of lifetime from below 1 µs to about 20 µs and a reduction of interstitial iron concentration from 1.32 × 1013 at/cm3 to 8.4 × 1010 at/cm3 are demonstrated in this paper.Peer reviewe
Numerical simulations of rear point-contacted solar cells pn 2.2 Wcm p-type c-Si substrates

Rear surface of high-efficiency crystalline silicon solar cells is based on a combination of dielectric passivation and point-like contacts. In this work, we develop a 3D model for these devices based on 2.2 Ωcm p-type crystalline silicon substrates. We validate the model by comparison with experimental results allowing us to determine an optimum design for the rear pattern. Additionally, the 3D model results are compared with the ones deduced from a simpler and widely used 1D model. Although the maximum efficiency predicted by both models is approximately the same, large deviations are observed in open-circuit voltage and fill factor. 1D simulations overestimate open-circuit voltage because Dember and electrochemical potential drops are not taken into account. On the contrary, fill factor is underestimated because of higher ohmic losses along the base when 1D analytical model is used. These deviations are larger for relatively low-doped substrates, as the ones used in the experimental samples reported hereby, and poor passivated contacts. As a result, 1D models could mislead to too short optimum rear contact spacing.Peer ReviewedPostprint (published version
Degradation of interfacial adhesion strength within photovoltaic mini-modules during damp-heat exposure

This is an Open Access Article. It is published by John Wiley and Sons Ltd under the Creative Commons Attribution 3.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/3.0/The degradation of adhesion strength between the back sheet and encapsulant due to moisture penetration has been investigated for commercial crystalline silicon photovoltaic mini-modules. The damp-heat tests originating from the International Electrotechnical Commission qualification test were carried out at five different temperature and relative humidity (RH) conditions (95 °C/85% RH, 85 °C/85% RH, 65 °C/85% RH, 85 °C/65% RH and 85 °C/45% RH). The adhesion strength was measured by 90° peel tests, carried out at specified time intervals during degradation. Several visible defects were observed, including delamination, moisture ingress and bubble formation. The adhesion strength showed a stretched exponential decay with time, and significant influence of test conditions was demonstrated. A humidity dose model was proposed by assuming micro-climates seen by the modules, that is, surface relative humidity of the back sheet as the driving factor for an Arrhenius-based model using temperature as accelerating factor. The correlation between adhesion strength degradation and humidity dose was investigated through linear and exponential models. Results showed that the conventional linear model failed to represent the relationship while the exponential model fitted to this correlation with extracted activation energy (Ea) of around 63 kJ/mol. This provides a model for the estimation of adhesion strength decay in dependence of the humidity conditions
Co-optimization of SnS absorber and Zn(O,S) buffer materials for improved solar cells

Thin-film solar cells consisting of earth-abundant and non-toxic materials were made from pulsed chemical vapor deposition (pulsed-CVD) of SnS as the p-type absorber layer and atomic layer deposition (ALD) of Zn(O,S) as the n-type buffer layer. The effects of deposition temperature and annealing conditions of the SnS absorber layer were studied for solar cells with a structure of Mo/SnS/Zn(O,S)/ZnO/ITO. Solar cells were further optimized by varying the stoichiometry of Zn(O,S) and the annealing conditions of SnS. Post-deposition annealing in pure hydrogen sulfide improved crystallinity and increased the carrier mobility by one order of magnitude, and a power conversion efficiency up to 2.9% was achieved.Engineering and Applied Science
Assessment of photovoltaic junction position using combined focused ion beam and electron beam-induced current analysis of close space sublimation deposited CdTe solar cells.

A major limitation of the cross‐section electron beam‐induced current method—the use of roughly fractured surfaces to provide the cross‐section—has been overcome with the use of focused ion beam microscope sample preparation. Using this method, it was possible to undertake a study of the relation between junction position and the corresponding external quantum efficiency (EQE) curves. For the case of cadmium telluride (CdTe) cells, it was demonstrated that the EQE curve shape that indicates a buried CdTe homojunction only arises if the junction is buried by more than 0.9 µm from the heterointerface. This highlights the limitations of interpreting EQE curve shape to determine junction position. It was also shown that extended postgrowth annealing degrades the cadmium sulfide by Kirkendall voiding, and this leads to efficiency loss
Time resolved investigation of Cu In,Ga Se2 growth and Ga gradient formation during fast selenization of metallic precursors

Ga segregation at the backside of Cu In,Ga Se2 solar cell absorbers is a commonly observed phenomenon for a large variety of sequential fabrication processes. Here, we investigate the correlation between Se incorporation, phase formation and Ga segregation during fast selenisation of Cu In Ga precursor films in elemental selenium vapour. Se incorporation and phase formation are analysed by real time synchrotron based X ray diffraction and fluorescence analysis. Correlations between phase formation and depth distributions are gained by interrupting the process at several points and by subsequent ex situ cross sectional electron microscopy and Raman spectroscopy. The presented results reveal that the main share of Se incorporation takes place within a few seconds during formation of In Se at the top part of the film, accompanied by outdiffusion of In out of a ternary Cu In Ga phase. Surprisingly, CuInSe2 starts to form at the surface on top of the In Se layer, leading to an intermediate double graded Cu depth distribution. The remaining Ga rich metal phase at the back is finally selenised by indiffusion of Se. On the basis of a proposed growth model, we discuss possible strategies and limitations for the avoidance of Ga segregation during fast selenisation of metallic precursors. Solar cells made from samples selenised with a total annealing time of 6.5 amp; 8201;min reached conversion efficiencies of up to 14.2    total area, without anti reflective coating . The evolution of the Cu In,Ga Se2 diffraction signals reveals that the minimum process time for high quality Cu In,Ga Se2 absorbers is limited by cation ordering rather than Se incorporatio
Insights into corrosion in dye solar cells

The main issue in using low cost metals in dye solar cells is the corrosion caused by the liquid electrolyte. Contrary to typical applications of metals, the adverse effects of corrosion in dye solar cells are related to irreversible depletion of charge carriers from the electrolyte rather than consumption of the metal itself. It is calculated that the penetration rate due to corrosion should not exceed 10−4 mpy (a couple of nanometers per year) to ensure device lifetime longer than 1 year. This is 10 000 times slower rate than what is considered to be a general benchmark value for very low corrosion rate in the field of corrosion science and has a major effect on how corrosion should be investigated in the case of dye solar cells. Different methods, their applicability, and limitations to investigate corrosion in dye solar cells are evaluated here. The issue with most techniques is that they can detect metals that are clearly corroding, but they have significant limitations in proving a metal stable. Our investigation shows that the most reliable information on corrosion is obtained from complete dye solar cells that are exposed to working conditions. A combination of color analysis of the electrolyte to such measurement is proposed as a means to extrapolate future performance of the cells and estimate potential lifetimes of the dye solar cells in regards to corrosion.Peer reviewe
Photonic crystal microcrystalline silicon solar cells

Enhancing the absorption of thin-film microcrystalline silicon solar cells over a broadband range in order to improve the energy conversion efficiency is a very important challenge in the development of low cost and stable solar energy harvesting. Here, we demonstrate that a broadband enhancement of the absorption can be achieved by creating a large number of resonant modes associated with two-dimensional photonic crystal band edges. We utilize higher-order optical modes perpendicular to the silicon layer, as well as the band-folding effect by employing photonic crystal superlattice structures. We establish a method to incorporate photonic crystal structures into thin-film (~500 nm) microcrystalline silicon photovoltaic layers while suppressing undesired defects formed in the microcrystalline silicon. The fabricated solar cells exhibit 1.3 times increase of a short circuit current density (from 15.0 mA/cm2 to 19.6 mA/cm2) by introducing the photonic crystal structure, and consequently the conversion efficiency increases from 5.6% to 6.8%. Moreover, we theoretically analyze the absorption characteristics in the fabricated cell structure, and reveal that the energy conversion efficiency can be increased beyond 9.5% in a structure less than 1/400 as thick as conventional crystalline silicon solar cells with an efficiency of 24%
High efficiency black silicon Interdigitated Back Contacted solar cells on p- and n-type c-Si substrates

This work demonstrates the high potential of Al2O3 passivated black silicon in high-efficiency interdigitated back contacted\ud
(IBC) solar cells by reducing surface reflectance without jeopardizing surface passivation. Very low reflectance values, below\ud
0.7% in the 300–1000 nm wavelength range, together with striking surface recombination velocities values of 17 and\ud
5 cm/s on p-type and n-type crystalline silicon substrates, respectively, are reached. The simultaneous fulfillment of requirements,\ud
low reflectance and low surface recombination, paves the way for the fabrication of high-efficiency IBC Si solar\ud
cells using black silicon at their front surface. Outstanding photovoltaic efficiencies over 22% have been achieved both\ud
in p-type and n-type 9-cm2 cells. 3D simulations suggest that efficiencies of up to 24% can be obtained in the future with\ud
minor modifications in the baseline fabrication process.Peer ReviewedPostprint (published version
Evolution of silicon bulk lifetime during III-V-on-Si multijunction solar cell epitaxial growth

The evolution of Si bulk minority carrier lifetime during the heteroepitaxial growth of III–V on Si multijunction solar cell structures via metal-organic chemical vapor deposition (MOCVD) has been analyzed. In particular, the impact on Si lifetime resulting from the four distinct phases within the overall MOCVD-based III–V/Si growth process were studied: (1) the Si homoepitaxial emitter/cap layer; (2) GaP heteroepitaxial nucleation; (3) bulk GaP film growth; and (4) thick GaAsyP1-y compositionally graded metamorphic buffer growth. During Phase 1 (Si homoepitaxy), an approximately two order of magnitude reduction in the Si minority carrier lifetime was observed, from about 450 to ≤1 µs. However, following the GaP nucleation (Phase 2) and thicker film (Phase 3) growths, the lifetime was found to increase by about an order of magnitude. The thick GaAsyP1-y graded buffer was then found to provide further recovery back to around the initial starting value. The most likely general mechanism behind the observed lifetime evolution is as follows: lifetime degradation during Si homoepitaxy because of the formation of thermally induced defects within the Si bulk, with subsequent lifetime recovery due to passivation by fast-diffusing atomic hydrogen coming from precursor pyrolysis, especially the group-V hydrides (PH3, AsH3), during the III–V growth. These results indicate that the MOCVD growth methodology used to create these target III–V/Si solar cell structures has a substantial and dynamic impact on the minority carrier lifetime within the Si substrate
Probabilistic evaluation of solar photovoltaic systems using Bayesian Networks: a discounted cash flow assessment

This paper was published by John Wiley & Sons Ltd as Open Access with a CC BY 4.0 licence.Solar PV technology (PV) is now a key contributor worldwide in the transition towards low carbon\ud
electricity systems. To date, PV commonly receives subsidies in order to accelerate adoption rates by\ud
increasing investor returns. However, many aleatory and epistemic uncertainties exist with regards\ud
these potential returns. In order to manage these uncertainties, a probabilistic approach using\ud
Bayesian networks has been applied to the techno-economic analysis of domestic solar PV.\ud
Using the UK as a representative case study, empirical datasets from over 400 domestic PV systems,\ud
together with national domestic electricity usage datasets, have been used to generate and calibrate\ud
prior probability distributions for PV yield and domestic electricity consumption respectively for typical\ud
urban housing stock. Subsequently, conditional dependencies of PV self-use with regards PV\ud
generation and household electricity consumption have been simulated via stochastic modelling using\ud
high temporal resolution demand and PV generation data. A Bayesian network model is subsequently\ud
applied to deliver posterior probability distributions of key parameters as part of a discounted cash\ud
flow analysis. The results indicate the sensitivity of investment returns to specific parameters\ud
(including PV self-consumption, PV degradation rates and geographical location), and quantify\ud
inherent uncertainties when using economic indicators for the promotion of PV adoption. The results’\ud
implications for potential rates of sector-specific adoption are discussed, and implications for policy makers globally are presented with regards energy policy imperatives, as well as fiscal imperatives of\ud
meeting investors’ requirements in terms of returns on investment in a post-subsidy context