bluuebunny/crossref_metadata_2025_split huggingface dataset:
Science and Technology of High Efficiency Solar Cells and Materials
Authors: Yamaguchi Masafumi 
Published: February 2020

Solar photovoltaics are expected to contribute as one of major energy sources in the future. For this end, further development of high-efficiency, low-cost and high reliable solar cells, materials, modules and systems is necessary.
This paper reviews fundamentals of solar cells and materials and present recent R&D status of various solar cells and materials and their future. In order to realize high efficiency and highly reliable solar cells, understanding and controlling imperfections (defects) are very important. There are several loss mechanisms to be solved for realizing high-efficiency and highly reliable solar cells. 1) bulk recombination loss, 2) surface recombination loss, 3) interface recombination loss, 4) voltage loss, 5) fill factor loss, 6) optical loss, 7) insufficient –energy photon loss. Key technologies for reducing the above losses are high quality film growth, reduction in density of defects, optimization of carrier concentration in base and emitter layers, double-hetero (DH) junction structure, lattice-matching of active layers and substrate, surface and interface passivation, reduction in series resistance and leakage current, anti-reflection coating, photon recycling and so forth.
The multi-junction solar cells have high efficiency potential of more than 50% due to wide photo response, while limiting efficiencies of single-junction solar cells are 31-32%. In order to realize high efficiency multi-junction (MJ) solar cells, understanding and controlling imperfections (defects) are also very important. The key issues for realizing super-high-efficiency MJ solar cells are 1) sub cell material selection, 2) tunnel junction for sub cell interconnection, 3) lattice-matching, 4) carrier confinement, 5) photon confinement, 6) anti-reflection in wide wavelength region and so forth. For concentrator applications by using MJ cells, the cell contact grid structure should be designed in order to reduce the energy loss due to series resistance, and tunnel junction with high tunnel peak current density is necessary. Because cell interconnection of sub-cells is one of the most important key issues for realizing high-efficiency MJ solar cells, effectiveness of double hetero structure tunnel diode is also presented in this paper.
Present status of various solar cells efficiencies are presented: 46.0% for concentrator III-V compound 4-junction solar cell, 38.8% for 1-sun III-V compound 4-junctiion cell, 25.6% for single-crystal Si cell, 21.7% for CIGS cell, 21.5% for CdTe cell, 20.1% for Perovskite cell, 13.6% for a-Si based 3-junction cell, 11.9% for dye-sensitized cell and 11.1% for organic cell. Efficiency potential of various solar cells is also discussed.
Vertically Aligned Hollow TiO2 Shell Protected SnO2 Nanorods By Atomic Layer Deposition for Highly Stable Lithium Storage
Authors: Carvajal Christian G , Rout Sangeeta , Mundle Rajeh , Bahoura Messaoud , Pradhan Aswini K 
Published: February 2020

Lithium-Ion batteries have shown a significant evolution in the last years regarding energy density and cycling life. Semiconductor nanomaterials such as tin oxide (SnO2) and similar metal-oxide materials such as titanium oxide (TiO2) are gaining significant attention for technologic innovations because of its Li storage stability. Our current study investigates vertically aligned SnO2 nanorods cycling stability for Li-ion batteries and TiO2 integration via atomic layer deposition (ALD) using the stop-valve configuration. 40nm film of ZnO was used as sacrificial layer to create in-tube SnO2 hollow TiO2 shell in vertically oriented nanorods configuration. Stainless steel battery spacer discs were used as substrates for the nanorods growth and coin cell half batteries were fabricated for the anodic Li storage studies. Li foil was used as the counter electrode and the batteries were charged and discharged from 0.1V to 2.5V for 75 cycles. Structural characterization along with the electrochemical study of the material demonstrated a higher capacity retention and improvement in cycling stability due to a better shape preservation during the lithiation process in comparison to the conventional vertical SnO2 nanorods anode configuration. Half battery cycling characterization and structural SEM comparisons and methods are described in detail.
Degradation and Stabilization of Lithium Cobalt Oxide in Aqueous Electrolytes
Authors: Ramanujapuram Anirudh , Gordon Daniel , Nitta Naoki , Magasinski Alexandre , Ward Brian , Huang Cindy , Yushin Gleb 
Published: February 2020

Lithium cobalt oxide (LCO) has long been proven to be an excellent material for cathodes in organic electrolytes [1]. It has shown high volumetric capacity and good stability in non-aqueous environments of commercial lithium-ion (Li-ion) batteries. Unfortunately, the flammability of organic electrolytes in combination with a special propensity for batteries constructed with LCO to experience thermal runaway creates safety concerns [2].
Here we discuss the exceptional electrochemical performance characteristics and stability of LCO in aqueous electrolytes. Aqueous electrolytes offer greatly improved safety and lower cost. In addition, they exhibit higher ionic motilities for the Li+ions and thus can be potentially used for faster charging batteries [3] or batteries with thicker electrodes. While LCO has been demonstrated to cycle for 20-100 cycles in aqueous environments [4, 5], the causes of its degradation have not been investigated in detail.
In our previous work we have demonstrated promising characteristics of lithium iron phosphate (LFP) cathodes in aqueous electrolytes [6]. Here we further expanded our studies and demonstrated LCO cathodes with remarkably stable performance showing only 13 % fading after over 1500 cycles.
Post mortem analysis of the electrodes was conducted to understand the effect of cycling and the causes of degradation. A powerful combination of X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM) Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD) have been utilized. Our systematic studies and post-mortem analyses of LCO cells reveal that the primary mechanism of LCO degradation in aqueous electrolytes is the formation of a resistive layer of cobalt (II) oxide on the particles’ surfaces. Electrolyte composition was found to have a dramatic impact on the electrochemical performance and stability of LCO in aqueous environments.
These results were recently accepted for publication in the Energy and Environmental Science Journal [7]. This talk will provide an overview of our findings and provide guidance for the future designs of aqueous electrochemical cells with stable cathodes.

References:

1.
J. Zhang, Y.J. Xiang, Y. Yu, S. Xie, G.S. Jiang, C.H. Chen
*, Journal of Power Sources 132 (2004) 187–194

2.
J.R. Dahn, E.W. Fuller, M. Obrovac, U. von Sacken, Solid State Ionics 69 (1994,) 265-270

3.
Y. Wang, J. Yi , and Y. Xia*, Advanced Energy Materials 2012, 2, 830–840

4.
G. Wang, L. Fu, N. Zhao, L. Yang, Y. Wu,* and H. Wu, Angew. Chem. Int. Ed. 2007, 46, 295–297

R. Ruffo, C. Wessells, R. A. Huggins, Yi Cui*,
Electrochemistry Communications 11 (2009) 247–249

6.
D. Gordon, Y. Wu, A. Ramanujapuram, J. Benson, J.T. Lee, A. Magasinski, N. Nitta, J. Huang and G. Yushin, Advanced Energy Materials (2015) 1501805

7.
A. Ramanujapuram, D. Gordon, A. Magasinski, B. Ward, N. Nitta, C. Huang, G. Yushin, Energy and Environmental Science (2016) [in press]
A New Method for Analyzing Transient Response of Hydrogen Permeation in Carbon Steel Sheet
Authors: Yamamoto Yudai , Jin Misako , Kitagawa Yuichi , Nakanishi Takayuki , Hasegawa Yasuchika , Fushimi Koji 
Published: February 2020

In acidic media, corrosion of steel is accompanied by hydrogen evolution reaction and a part of adsorbed hydrogen atoms penetrates into the steel, causing hydrogen embrittlement. There are strong needs to elucidate mechanism and kinetics of hydrogen penetration for inhibiting hydrogen embrittlement. Conventionally, a diffusion coefficient of hydrogen atoms in steel sheet samples was estimated using so-called Devanathan-Stachurski (DS) cell.1 The authors have modified the DS cell with an electrolyte-flow channel in the entry side cell and discovered that the disturbance in a flow-rate causes a similar perturbation in hydrogen exit current i
exit as well as hydrogen entry current i
entry.2 When a sinusoidal wave perturbation was applied to flow-rate, i
entry and i
exit showed sinusoidal waveforms with phase shifts
θ
depending on the perturbation frequency. The phase shift was arisen from a diffusional delay in i
exit and could be utilized as a new parameter to discuss the diffusivity of hydrogen atoms in the sample sheets.
In previous researches, however, we only focused on the steady value of phase shifts and did not discuss about time-dependent information of the shifts in detail. In this study, we newly developed a method to realize a real-time evaluation of phase shift by fast-Fourier-transform (FFT). We also conducted transient analyses on phase shifts to elucidate more about hydrogen penetration mechanism in carbon sheet.
During a series of hydrogen permeation measurement of polycrystalline steel sheet samples, a phase shift obtained by the FFT calculation was gradually increased with measurement time. From an algebraic calculation on diffusion phenomena with sinusoidal perturbation and the previous report,3, 4 the value of θ depends on perturbation frequency f, sheet thickness L, diffusion coefficient D, showing a relationship of θ = tan-1(tan α tanh α) where α = (πfL2
/D)1/2. In the case where the values of f and L are fixed throughout the measurement, therefore, the experimental result indicates that the value of D is gradually decreased. This result suggests the existence and its effect of hydrogen trapping sites in the sample sheet.
References
1. M.A.V. Devanathan and Z. Stachurski, Proc. R. Soc. Lond. A,
270, 90 (1962).
2. K. Fushimi, M. Jin, T. Nakanishi, Y. Hasegawa, T. Kawano and M. Kimura, ECS Electrochem. Lett.,
3, C21 (2014).
3. K. Sekine, Chem. Lett.,
4, 841 (1975).
4. Y. Yamamoto, M. Jin, Y. Kitagawa, T. Nakanishi, Y. Hasegawa and K. Fushimi, ISIJ Int.,
56, 474 (2016).
Anodic Oxides Layers: Synthesis and Formation of Composites for Energy Storage Devices
Authors: Kowalski Damian 
Published: February 2020

The anodizing is a high-voltage electrochemical conversion process that forms barrier-type oxides or nanoporous/nanotubular layers on valve metals and alloys mainly depending on the composition of electrolyte used.[1] The key to achieve the ordered nanoporous/nanotubular structures is a displacement of the film material above the original surface position due to synergistic effect of pits generation (field assisted oxide dissolution), stress generated at the metal-oxide interface including electrostriction and plastic oxide flow switching the growth of the barrier-film to nanotube/nanopore. Typically, the TiO2nanotube array formed in organic electrolytes such as glycerol, dimethyl sulfoxide, ethylene-glycol is obtained in the form of close packed structure in which the nanotubes nearly stick together with the tube walls. A fundamentally different nanostructure from that is obtained in diethylene-glycol electrolyte. The nanostructure is characterized by free standing nanotubes separated by an interconnecting space much bigger than the thickness of nanotube wall (Fig. 1). [2,3] Such geometry gives possibility for formation of composites with secondary materials using electrochemical deposition in view of improved wetting behavior for the nanostructure. [4] Herein we report on how to control the synthesis of nanotubes to achieve unique oxide geometries, we discuss functional properties of nanostructures and report an examples of composites formed between oxide layer and Si, CdSe, Au, Pt. An examples of the nanostructured energy storage devices will be demonstrated. [5]
References:
[1] D. Kowalski, D. Kim and P. Schmuki, Nano Today, 8(2013) 235.
[2] D. Kowalski, J. Mallet, J. Michel, and M. Molinari, J.Mater.Chem.A
3(2015) 6655.
[3] D. Kowalski, J. Mallet, S. Thomas, J. Rysz, B. Bercu, J. Michel and M. Molinari, Electrochim. Acta, (2016), 10.1016/j.electacta.2016.02.213.
[4] D. Kowalski, and P. Schmuki, Chem. Comm., 46(2010) 8585.
[5] D. Kowalski, J. Mallet, S. Thomas, A. Woreka, J. Michel, M. Molinari, C. Guery, and M. Morcrette Suubmitted (2016)
Fig. 1 SEM and TEM images for TiO2 nanotubes formed at 60V and 70V for 16h in diethylene glycol electrolyte containing 0.1M HF and H2O 2-4 wt.%. The right figure shows STEM and TEM images for Si electrodeposited on TiO2nanotubes and applied as negative electrode in lithium ion battery.

Figure 1
In-Situ Corrosion Monitoring of Iron and Zinc in Atmospheric Environments
Authors: Omoda Masataka , Mizuno Daisuke , Ishikawa Nobuyuki 
Published: February 2020

Traditionally, for evaluating corrosion resistance of materials used in atmospheric conditions, exposure tests in the actual environment and accelerated corrosion tests in the laboratory have been widely used. Till now, it has been very difficult to estimate in detail corrosion rate variations caused by the change of each environmental factor such as temperature, relative humidity, amount of airborne sea salt during the test periods. Also, it requires a long time period to evaluate the corrosivity in actual corrosive atmospheric environments. For these reasons, an in-situ corrosion monitoring technique is useful. Time variation of corrosion rate has been successfully monitored by using an electrical resistance corrosion sensor, which converts the increase of electrical resistance caused by metal consumption to corrosion loss. Additionally, a new accelerated corrosion test was authorized as ISO 16539 Method B on March 1, 2013. This test has good correlation with corrosion behavior in an actual corrosive atmospheric environment. In this study, the details of the corrosion rate of steel and zinc were evaluated by the accelerated corrosion test (ISO 16539 Method B) and atmospheric exposure test. In addition, the relation between corrosion rate and each environmental factor was analyzed.
Two kinds of electrical resistance corrosion sensors, an Fe sensor (250 µm thick) and a Zn sensor (50 µm thick), were used. In the accelerated corrosion test (ISO16539-Method B), the corrosion depth as evaluated by the sensors displayed a good correlation with that of the exposure test samples. The variation in the corrosion rate could be evaluated by the sensors. And also, it was confirmed that the corrosion rate increased during the wet stage and decreased during the dry stage in both sensors. In exposure tests in Okinawa and Kawasaki, the variation of the corrosion rate due to the effects of changeable environmental conditions throughout the year could be evaluated by the sensors. Okinawa is seashore area at the s southern island in Japan, and Kawasaki is industrial area in Japan. The corrosion rate in Okinawa as evaluated by the Fe sensor was greater than that found in Kawasaki. However, the corrosion rate in Okinawa as evaluated by the Zn sensor was almost the same as that in Kawasaki. The corrosion sensors could clarify the difference in corrosion behavior between steel and zinc. Furthermore, the relationship between the corrosion rate and the environmental factors (temperature, relative humidity, amount of airborne sea salt, etc.) was analyzed. The corrosion rate of steel had a positive relation with temperature, relative humidity and airborne sea salt. The dependence of corrosion rate of zinc on environmental factors was also investigated. Comparison of corrosion behavior and its dependence of environmental factors between iron and zinc will be discussed.
Increased Corrosion Resistance of Zinc Magnesium Aluminum Galvanised Coating through Germanium Additions
Authors: Mehraban Shahin 
Published: February 2020

Improvements in the corrosion resistance of hot dipped galvanised steel coatings have been brought about over the last 20 years through binary alloy additions such as Al and more recently ternary Mg additions [1], [2], to further improve corrosion resistance quaternary additions were made to a commercially produced Zn-Mg-Al (ZMA) alloy.
Corrosion performance of the ZMA alloy coating was shown to improve through the addition of a quaternary element, Germanium. This was added in the molten state and the alloy mixture was rapidly cooled to mimic the cooling rate of a galvanised steel production line.
The increased corrosion resistance can be attributed to microstructural changes in the alloy composition due to Ge addition while in the molten state. The proportion of the most active MgZn2 phase which has been shown to initiate the corrosion reaction in a ZMA alloy [3] was reduced thorough the formation of Mg2Ge crystals. The formation of crystal structures within the alloy also increased the heterogeneous nucleation of the primary zinc phase.
The phases present of the experimental alloy were identified using EDX analysis and from this a relationship was determined between the observed microstructural phases and the corrosion rates for varying Ge addition.
The Scanning Vibrating Electrode Technique (SVET) was used to measure the rate of corrosion, anode life and zinc loss of the alloy samples. The results showed a zinc loss of around 50% when compared to standard ZMA alloy without Ge addition.

[1] D. A. Worsley, H. N. McMurray, J. H. Sullivan, and I. P. Williams, “Quantitative Assessment of Localized Corrosion Occurring on Galvanized Steel Samples Using the Scanning Vibrating Electrode Technique,” Corrosion, vol. 60, no. 5, pp. 437–447, May 2004.
[2] A. R. Marder, “The metallurgy of zinc-coated steel,” Prog. Mater. Sci., vol. 45, no. 3, pp. 191–271, Jun. 2000.
[3] J. Sullivan, S. Mehraban, and J. Elvins, “In situ monitoring of the microstructural corrosion mechanisms of zinc–magnesium–aluminium alloys using time lapse microscopy,” Corrosion Science, vol. 53, no. 6, pp. 2208- 2215, Jun. 2011.
Opto-Electronic Properties of Hybrid Perovskites
Authors: Mohite Aditya , Nie Wanyi , Tsai Hsinhan , Blancon Jean-Christophe , Tretiak Sergei , Gupta Gautam 
Published: February 2020

The photovoltaic efficiency utilizing hybrid perovskites as an absorber layer have reached 22% and offers extraordinary potential for clean sustainable energy technologies and also for low-cost optoelectronic devices. In spite of the unprecedented progress, there still exists tremendous variability in the structural and physical properties of these hybrid perovskite based thin-films across the globe. Crystallinity, defect density and impurities are in general determining factors for these physical properties, which are also highly dependent on the materials formation processes. In addition to this, the stability and reliability of perovskite based devices remains open questions and perhaps will determine the fate of this remarkable technology in the longer run.
In this talk, I will describe our recently discovered hot-casting approach for thin-film crystal growth as a general strategy for growing highly crystalline, bulk homogenous pin-hole free thin-films of both 3D and layered 2D organometallic perovskites that yield reproducible and stable high efficiency devices and allow access to the intrinsic photo-physical properties. These results are briefly described below.
Photovoltaic devices fabricated using 3D hybrid perovskites show hysteresis-free response, with high degree of reproducibility, with an average efficiency of planar devices approaching ~20%. Photo-physical, electrical characterization and theoretical modeling attribute the improved performance to reduced bulk defects and improved charge-carrier mobility in large-grain devices. Furthermore, our most recent efforts on understanding and controlling photo-degradation in these systems demonstrate that the large grain-size perovskite thin-films are not limited by detrimental effects such as ion migration or defect assisted trapping generally reported in perovskite thin-film devices allowing us to probe intrinsic photo-physical processes that lead to the degradation of PCE in perovskite solar cells and control the light-induced degradation in these materials.
Vapor-Assisted Efficient Perovskite Solar Cells Fully Fabricated in Open Air
Authors: Yin Jun , Li Jing , Zheng Nanfeng 
Published: February 2020

Organometal trihalide perovskite based solar cells (PSCs) have been developed intensively in recent years due to the attractive applications in the next generation solar cells with low cost and high power conversion efficiency (PCE).1, 2 Currently, the solution based spin-coating technique is the mostly used preparing method for perovskite films.3, 4 However, limited film scale, low material usage and strict film growth condition always present in the spin-coating based fabrication processes. Like other thin-film solar cells, vapor-depositing method also can be used in the PSCs' fabrication to improve the film quality and interface uniformity, where the growth process can be much precisely controlled under vapor mode transportation. 5

In this work, vapor assisted deposition of organometal trihalide perovskite films in open air has been developed to fabricate efficient and stable perovskite solar cells. It has been found that the film quality, as well as the device’s performances, are strongly dependent on the reaction time and growth temperature, while not sensitive to the environment humidity. With the optimized vapor-assisted growth parameters, an average PCE of 16.40% and the maximum of 18.14% have been achieved on the planar type of PSCs. Detailed investigations demonstrated that the improved film quality and interface uniformity within cells by this unique vapor-assisted method are responsible for the enhanced photovoltaic performances and good stability either in air or under light irradiation.

References

1. M. A. Green, A. Ho-Baillie and H. J. Snaith, Nature Photon., 2014, 8, 506-514.
2. M. M. Lee, J. Teuscher, T. Miyasaka, T. N. Murakami and H. J. Snaith, Science, 2012, 338, 643-647.
3. H. S. Jung and N. G. Park, Small, 2015, 11, 10-25.
4. J.-H. Im, H.-S. Kim and N.-G. Park, APL Materials, 2014, 2, 081510.
5. M. Liu, M. B. Johnston and H. J. Snaith, Nature, 2013, 501, 395-398.