Nickel Oxide Layer Research Articles

NiO thin films synthesized by sol-gel: Potentiality for the realization of antireflection layer for silicon based solar cell applications

In this work we present a study on the effect of nickel oxide (NiO) thin films deposited by sol-gel technique on the optical reflectivity of silicon substrates with and without a thin porous layer. Up to six layers of NiO have been deposited at the same optimized experimental conditions. The as-deposited films were pre-heated at 300°C for 10min and then annealed in ambient atmosphere at 600°C for 1h The reflectivity spectra were measured by using a UV–vis spectrophotometer. The reflectivity of the untreated silicon is about 45% within 300–1200nm spectral range. It was found that the reflectivity decreases after the deposition of the NiO thin layers. The minimum value of the reflectivity (about 15%) is obtained after the deposition of two layers of NiO. For a higher number of NiO layers, the reflectivity increases but remains still lower than that of the untreated silicon. Then, after the optimization on the number of layers, NiO thin films are treated at various temperatures after being deposited at the same experimental conditions. The Surface morphology of the NiO films was investigated by atomic force microscopy (AFM). The surface morphology of the NiO thin films has a pyramidal nano-textured surface and changes by varying the number of layers. The porous silicon thin films were elaborated using the chemical vapor etching technique. It was found that the total reflectivity decreases by increasing the etching time. The optimal result corresponding to a reflectivity of 12% was obtained by combination of NiO and PS to form NiO/PS structure.

Electrodeposition of NiO Films and Inverse Opal Organized Layers from Polar Aprotic Solvent-Based Electrolyte

The implementation of polar aprotic organic solvents remains almost unexplored for the direct electrochemical deposition (ECD) of nickel oxide dense or mesoporous thin films and organized macroporous structures. In the present work, the electrochemical deposition of this oxide in dimethyl sulfoxide (DMSO) medium by cathodic reduction of nickel nitrate hexahydrate is investigated. The electrochemical phenomena involved in the deposition process have been analyzed by cyclic voltammetry (CV). It is shown that the ECD process occurs below −0.80V/SCE. The gas atmosphere for the deposition and salt dissolution was found important parameters for the electroactivity of the system and the best conditions for ECD have been defined. Raman spectroscopy has shown the direct NiO deposition. Moreover, the crystallization and higher ordering occuring through thermal annealing has been followed by the 2-magnon Raman band of NiO. The difficulty of obtaining well-crystallized pure phase without metallic nickel was stressed by the X-ray diffraction study and thermogravimetry of the layers. We have shown that annealing the sample at 450°C resulted in oxidation and crystallization and in the formation of a mesoporous morphology. The electrochemical activity and electrochromism of the layers has been investigated by CV in alkaline aqueous solution. Finally, we have prepared opal inverse organized structures with a perfectly defined macropore organization and size using a macrosphere polystyrene template. It has illustrated the high interest of the present electrodeposition technique for the preparation of nickel oxide layers with enhanced properties for advanced applications.

Efficient PbS QD solar cell with an inverted structure

Efficient PbS quantum dot (QD) solar cell with the traditional structure requires an inorganic buffer layer that is usually fabricated at high temperature, which is not compatible with the industrially preferential roll-to-roll fabrication process. Identification of a suitable buffer layer and efficient device construction are thus of particular significance. Herein, we fabricate PbS quantum dot solar cells in an inverted structure using poly(thiophene) (3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) as the anode buffer layer. The resulting devices present a high efficiency of 4.1%, among the best values of inverted PbS QD solar cells. Electrochemical and photoelectric characterizations have shown that, compared with high-temperature annealed nickel oxide (NiO) and vanadium pentoxide (V2O5) layers, the low-temperature processed PEDOT:PSS layer has a more compatible film properties for efficient injection and collection of charges from PbS QD active layer. Our work provides a promising strategy for fabrication of QD solar cells in an economical and efficient way.

Oxide evolution on Alloy X-750 in simulated BWR environment

In order to simulate the environment experienced by spacer grids in a boiling water reactor (BWR), specimens of the Ni-based Alloy X-750 were exposed to a water jet in an autoclave at a temperature of 286 °C and a pressure of 80 bar. The oxide microstructure of specimens exposed for 2 h, 24 h, 168 h and 840 h has been investigated mainly using electron microscopy. The specimens suffer mass loss due to dissolution during exposure. At the same time a complex layered oxide develops. After the longest exposure the oxide consists of two outer spinel layers consisting of blocky crystals, one intermediate layer of nickel oxide interspersed with Ti-rich oxide needles, and an inner layer of oxidized base metal. The evolution of the oxide leading up to this structure is discussed and a model is presented.

Fundamental physicochemical regularities of the chemical vapor deposition of nickel oxide layers

Physicochemical regularities of the chemical vapor deposition (CVD) of nickel oxide layers in the (EtCp)2Ni–O3–O2–Ar reaction system at a reduced pressure were studied. Dependences of growth rate of NiO layers on deposition temperature, linear gas flow velocity, and roughness were derived. A mass-spectrometric study of the composition of the reaction gas phases formed in these systems provided evidence about the fundamental physicochemical regularities of the CVD process, which is important for solving applied problems associated with the development of technological equipment and industrial technology for deposition of NiO layers.

Switching Hole and Electron Transports of Molecules on Metal Oxides by Energy Level Alignment Tuning.

Charge transport at organic/inorganic hybrid contacts significantly affects the performance of organic optoelectronic devices because the unfavorable energy level offsets at these interfaces can hinder charge injection or extraction due to large barrier heights. Herein, we report a technologically relevant method to functionalize a traditional hole-transport layer of solution-processed nickel oxide (NiOx) with various interlayers. The photoemission spectroscopy measurements reveal the continuous tuning of the NiOx substrate work function ranging from 2.5 to 6.6 eV, enabling the alignment transition of energy levels between the Schottky-Mott limit and Fermi level pinning at the organic/composite NiOx interface. As a result, switching hole and electron transport for the active organic material on the composite NiOx layer is achieved due to the controlled carrier injection/extraction barriers. The experimental findings indicate that tuning the work function of metal oxides with optimum energy level offsets can facilitate the charge transport at organic/electrode contacts.

Thin Metal Transparent Conductive Electrodes Formed by Oblique‐Angle Deposition

Oblique‐angle deposition (OAD) was recently developed for the fabrication of functional thin films with varying porosity and refractive index. In this study, OAD is used to fabricate excellent thin‐metal transparent conductive electrodes (Thin‐TCEs) with an optical transmittance of >93% at wavelengths of 450–550 nm, and sheet resistance of ≈14 Ω sq–1. The process involved the deposition of a thin Ni (5 nm)/Au (5 nm) bilayer with a tilt angle of 45°, and subsequent thermal annealing in ambient O2 to produce a 10 nm‐thick nickel oxide layer with very uniformly distributed Au nanoparticles, afforded by the enhanced interaction between the ambient gas and the metallic film. The application of the Thin‐TCE to III‐nitride light‐emitting diodes (LEDs) produced 15.4% higher output power and 0.05 V lower forward voltage compared to the reference LEDs. These results indicate that the Thin‐TCE is a promising potential replacement for the ITO TCE currently used in III‐nitride LEDs and organic optoelectronic devices, especially considering their fast and cheap fabrication process, availability for mass production, and better electrical and optical properties.

Optically transparent and electrically conductive NiO window layer for Si solar cells

Nickel oxide (NiO) material has been functionally applied for Si solar cells. Optically transparent and electrically conductive NiO was used as a window layer for Si solar cells to provide a relatively high efficiency of 15.37%. An optically transparent NiO layer was coated onto Si by large-area applicable sputtering deposition to give good crystalline structure. NiO-coating on Si spontaneously reduces the light reflection for visible range light, resulting in the improved current profiles. Due to the electrically low sheet resistance, the NiO-coating design is effective to improve the open circuit voltage and fill factor of solar cells. The optical and electrical benefits of NiO would provide a route of improvement for various photoelectric devices, including solar cells.

Oxide‐Modified Nickel Photocatalysts for the Production of Hydrocarbons in Visible Light

AbstractMetallic nickel nanostructures that were partially decorated by discrete nickel oxide layers were fabricated by in situ reduction of calcinated Ni‐containing layered double hydroxide nanosheets, the structure of which was confirmed by extended X‐ray absorption fine structure spectroscopy, X‐ray photoelectron spectroscopy, and transmission electron microscopy. The existence of the abundant interfaces between the surface Ni oxide overlayer and metallic Ni altered the geometric/electronic structure of the Ni nanoparticles, making them apt for CO activation under light irradiation. Most importantly, the unique structure favors the C−C coupling reaction on its surface, which confers the catalyst unexpected reaction power towards higher hydrocarbons at moderate reaction conditions. This study leads to a green and sustainable approach for the photocatalytic production of highly valuable chemical fuels.

Oxide-Modified Nickel Photocatalysts for the Production of Hydrocarbons in Visible Light.

Metallic nickel nanostructures that were partially decorated by discrete nickel oxide layers were fabricated by in situ reduction of calcinated Ni-containing layered double hydroxide nanosheets, the structure of which was confirmed by extended X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The existence of the abundant interfaces between the surface Ni oxide overlayer and metallic Ni altered the geometric/electronic structure of the Ni nanoparticles, making them apt for CO activation under light irradiation. Most importantly, the unique structure favors the C-C coupling reaction on its surface, which confers the catalyst unexpected reaction power towards higher hydrocarbons at moderate reaction conditions. This study leads to a green and sustainable approach for the photocatalytic production of highly valuable chemical fuels.

Optical and electrical effects of nickel oxide interlayer for anode-recessed organic light-emitting diodes

Forming a nickel oxide (NiOx) layer on recessed indium tin oxide (ITO) anodes has successfully enhanced the current efficiency of an organic light emitting diode (OLED) by up to 46%. The recesses largely increased the haze of ITO film and led to a 32.8% current efficiency enhancement of a planar OLED. The introduced NiOx interlayer allowed another 12.9% efficiency enhancement mainly due to lowered potential barrier at the ITO/organic interface and further elevated haze that led to a more efficient light extraction.

Self-assembled nanostructured resistive switching memory devices fabricated by templated bottom-up growth.

Metal-oxide-based resistive switching memory device has been studied intensively due to its potential to satisfy the requirements of next-generation memory devices. Active research has been done on the materials and device structures of resistive switching memory devices that meet the requirements of high density, fast switching speed, and reliable data storage. In this study, resistive switching memory devices were fabricated with nano-template-assisted bottom up growth. The electrochemical deposition was adopted to achieve the bottom-up growth of nickel nanodot electrodes. Nickel oxide layer was formed by oxygen plasma treatment of nickel nanodots at low temperature. The structures of fabricated nanoscale memory devices were analyzed with scanning electron microscope and atomic force microscope (AFM). The electrical characteristics of the devices were directly measured using conductive AFM. This work demonstrates the fabrication of resistive switching memory devices using self-assembled nanoscale masks and nanomateirals growth from bottom-up electrochemical deposition.

Fabrication technology of CNT-Nickel Oxide based planar pseudocapacitor for MEMS and NEMS

Fabrication technology of planar pseudocapacitor (PsC) based on carbon nanotube (CNT) forest, synthesized using plasma enhanced chemical vapor deposition (PECVD) method, covered with thin nickel oxide layer deposited by successive ionic layer adsorption and reaction (SILAR) method, is demonstrated. Dependences of deposited oxide layers thickness on device specific capacities is studied. It is shown that pseudocapacity of nickel oxide thin layer increases specific capacity of the CNT's based device up to 2.5 times.

Origin of temperature oscillations of nickel catalyst occurring in methane oxidation

The catalytic oxidation of methane over a nickel foil has been investigated in a wide range of methane: oxygen molar ratios at a constant reactor temperature of 680°C. Under oxygen-deficient conditions, the reaction takes place in the self-oscillating mode. Stable self-sustained oscillations of the methane oxidation rate are observed in the CH4: O2 molar ratio range from 2: 1 to 19: 1. This process is accompanied by catalyst temperature oscillations, whose amplitude reaches 80°C. It has been demonstrated by scanning electron microscopy that the origination of the self-sustained oscillations is accompanied by morphological changes in the catalyst surface. Under the action of the reaction medium, a porous layer 5–10 µm in thickness forms on the nickel foil surface. The mechanism of methane oxidation over nickel that accounts for the onset of the self-sustained oscillations is discussed. This mechanism is based on periodical nickel oxidation and reduction. When nickel is in the high-activity state, it is mainly in metallic form, and the passage of nickel into its low-activity state is accompanied by the formation of a nickel oxide layer on the foil surface. The reduction of this nickel oxide causes a periodic decrease in the catalyst temperature. The total and partial oxidations of methane on the reduced surface of the nickel foil raise the catalyst temperature. Under oxygen-deficient conditions, a carbon deposit builds up on the catalyst surface, and the combustion of this deposit complicates the catalyst temperature oscillation profile.

Photoelectrochemical characterization of squaraine-sensitized nickel oxide cathodes deposited via screen-printing for p-type dye-sensitized solar cells

In the present paper we report on the employment of the screen-printing method for the deposition of nickel oxide (NiOx) layers when preformed nanoparticles of the metal oxide (diameter<50nm) constitute the precursors in the paste. The applicative purpose of this study is the deposition of mesoporous NiOx electrodes in the configuration of thin films (thickness, l≤4μm) for the realization of p-type dye-sensitized solar cells (p-DSCs). Three different squaraine-based dyes (here indicated with VG1C8, VG10C8 and DS2/35), have been used for the first time as sensitizers of a p-type DSC electrode. VG1C8 and VG10C8 present two carboxylic groups as anchoring moieties, whereas DS2/35 sensitizer possesses four acidic anchoring groups. All three squaraines are symmetrical and differ mainly for the extent of electronic conjugation. The colorant erythrosine b (ERY B) was taken as commercial benchmark for the comparison of the different dye-sensitizers. The influence of the conditions of NiOx sensitization and of NiOx surface pre-treatment on the photoelectrochemical performance of the corresponding p-DSCs have been analyzed. The highest overall conversion efficiency achieved within this set of organic colorants was 0.025% with VG1C8 and VG10C8 as colorants when NiOx surface was pre-treated with alkali. The alkaline pre-treatment of the NiO surface led to the highest efficiencies of the incident photon-to-current conversion (IPCEMAX=11% at about 390nm) for the three squaraines here considered in correspondence of the wavelength of their maximum absorption. The prolongation of the sensitization time of NiOx cathodes up to 16h leads to a general increase of the open circuit voltage in the corresponding p-DSCs.

Crystallization mechanism and corrosion property of electroless nickel phosphorus coating during intermediate temperature oxidation

Electroless Ni–P coating was deposited on steel substrate and the effect of intermediate temperature oxidation on crystallization mechanism and corrosion properties of the coating was investigated. Ni–P coatings were annealed at three different temperatures, viz. 200°C, 400°C and 600°C for 2h in air. Formation of nickel oxide (NiO) was observed in the coating upon annealing beyond the crystallization temperature (330°C). Crystallization mechanism provided insight about the step by step formation of long range ordered Ni,Ni3P and NiO phases.Improvement in the corrosion resistance of Ni–P coating compared to bare steel was found to be ∼21% on annealing at 400°C in air which gradually increased to ∼31% on annealing the coating at 600°C in air. Increasedcorrosion resistance at 400°C annealed coating was attributed to the formation of crystalline Ni and Ni3P phases. Two simultaneously effects have been identified for the increased corrosion resistance of the coating annealed at 600°C in air. (a) Formation of NiO layer which acts as a passivation layer and protects the underlying P enriched layer and (b) absence of an interdiffusion layer from substrate to coating.

Exploration of Metal Oxide Catalysts for Direct Urine Fuel Cell and Gas Sensors for Its Condition Monitoring

The technology to use hydrogen as an attractive energy resource is in development. However, storage of hydrogen is still considered as a major drawback. An alternative approach has been investigated to use light chemicals as a hydrogen source such as methanol, ammonia or urea (1-4). Urea is a non-toxic and low-cost industrial product as well as naturally exists in urine and waste water. Urea / urine fuel cell can be applied to treatment of waste water, animal waste, waste supplier of manned spaceship, power of electrical vehicles and portable equipment (3). Since the mechanisms of chemical reaction on urine conversion are not well understood, an economic method to rapidly evaluate the chemical species inside the fuel cell can provide insights to understand the mechanisms. Among critical components to construct a fuel cell, catalyst can be an important material for urine/urea conversion. Nickel, an inexpensive transition metal, has been investigated as a catalyst for the urine / urea fuel cell. Boggs et al. (2) demonstrated the direct conversion of urine and urea to hydrogen using electrochemical oxidation with a nickel catalyst. Lan et al. (4) synthesized nanostructured nickel and applied it as an anode catalyst for fuel cells. Transition metal oxides also show catalytic processes due to their selectivity on oxidation, reduction and dehydrogenation (5). Electrochemical properties of nickel oxide has been studied to apply capacitors (6), electrochromic thin films (7), phenol degradation (8), and biosensors (9). Therefore, nickel oxide is considered as a potential catalyst of urea / urine oxidation. In this study, nanostructured nickel oxide is synthesized using a hydrothermal method and a precipitation method with different morphology. The crystal structure and morphology after calcination are shown in Fig. 1 and Fig. 2, respectively. Different ratios of mixtures with synthesized nickel oxide and graphene oxide are fabricated to films by electrophoretic deposition (EPD). Parameters in EPD were controlled to construct different hierarchical structures. The structural properties of the deposited nickel oxide layers are analyzed by using SEM and XRD. Then, the catalytic effects were also investigated. The use of gas sensors to measure cell reaction will be performed to advance fundamental understanding of direct conversion of urine. This research was partially supported by Agency for Defense Development (ADD) as global corporative research and Auburn University IGP. 1. Brown, L. F. (2001) International Journal of Hydrogen Energy 26, 381-397 2. Boggs, B. K., and Botte, G. G. (2009) Journal of Power Sources 192, 573-581 3. Lan, R., Tao, S., and Irvine, J. T. (2010) Energy & Environmental Science 3, 438-441 4. Lan, R., and Tao, S. (2011) Journal of Power Sources 196, 5021-5026 5. Kung, H. H. (1989) Transition metal oxides: surface chemistry and catalysis, Elsevier 6. Xing, W., Li, F., Yan, Z.-f., and Lu, G. (2004) Journal of Power Sources 134, 324-330 7. Kamal, H., Elmaghraby, E., Ali, S., and Abdel-Hady, K. (2005) Thin Solid Films 483, 330-339 8. Lai, T.-L., Lee, C.-C., Wu, K.-S., Shu, Y.-Y., and Wang, C.-B. (2006) Applied Catalysis B: Environmental 68, 147-153 9. Salimi, A., Sharifi, E., Noorbakhsh, A., and Soltanian, S. (2007) Biosensors and Bioelectronics 22, 3146-3153 Figure 1

Preparation and Characterization of Nickel and Copper Oxide/Hydroxide Films on Stainless Steels Substrates for Use as Cathodes in Alkaline Water Electrolysis

The production high purity hydrogen by water electrolysis based renewable sources as a mean to store energy, has gained some attention in the last years due to the high specific energy of hydrogen, the potentially neutral carbon and zero emission of the usage of H2as fuel. However, it remains certainly necessary to develop efficient and lower cost electrolyzers. Such a situation requires the search for and the development of inexpensive and stable electrode materials, showing low polarization to hydrogen evolution reduction (HER). In this work copper and nickel oxides were studied for use as electrodes for the reduction of hydrogen in alkaline water electrolysis. The nickel and copper oxide composites coatings were deposited electrochemically as oxides/hydroxides on a stainless steel (SS) electrode and characterized using electrochemical methods such as cyclic voltammetry (CV), cathodic polarization and Tafel slops. The HER was studied using as electrolytic cathodes unmodified AISI 304 stainless steel (SS), nickel coated stainless steel (SS/Ni), copper coated stainless steel (SS/Cu), and nickel (under layer) and copper (top layer) coated stainless steel (SS/Ni/Cu) in 5 M KOH solution. It was found that, the SS/Ni/Cu electrode presents good electrocatalytic activity and stability toward the HER, compared to the SS electrodes modified by single nickel oxide layer. This behavior seems be explained by the synergistic interaction of Ni and Cu with Fe present in the stainless steel.

Gas Sensing Behaviors of Hierarchically Structured Nickel Oxide Film By Electrophoretic Deposition

Over the past few years, the interest in wearable devices has increased dramatically. A highly miniaturized and wearable gas sensor system is one of interests. Integration of fabric and gas sensors for a wearable breath monitoring system would allow continuous monitoring patients’ breathe gases such as acetone gas for diabetes [1], ammonia for renal disease [2], and ethanol for hepatic steatosis [3]. Thus, there has been demands to fabricate wearable gas sensing system operating at daily environment. Semiconducting nano-scale metal oxides such as tin oxide [4], zinc oxide [5], and nickel oxide [6] have been developed to apply gas sensors. Among them, nickel oxide, which shows p-type behavior, has outstanding electrical and optical properties as well as chemical stability. There have been different approaches to synthesize nickel oxide films, such as physical and chemical vapor deposition. In this study, the particles with different morphology were first prepared by solution based synthesis method by using different precursors. Electrophoretic deposition (EPD) was then used to construct hierarchically structured NiO films. The nickel oxide was prepared by precipitation followed by calcination of nickel hydroxide-based precursors prepared by nickel acetate, nickel chloride or nickel nitrate. Morphology-tunable NiO nanoparticles were designed and prepared by heat treating different forms of nickel hydroxide precursors. By intercalating different size of anions (Cl- < NO3 - < CH3COO-) [7], different size and morphologies of precipitates are expected. The crystal structure and morphology by calcination are shown in Fig. 1 and Fig. 2, respectively. Each nickel oxide nanoparticles were coated to films by EPD process. Parameters in EPD were controlled to construct different hierarchical structures. The structural properties of the deposited nickel oxide layers are analyzed by using SEM and XRD. Then, gas sensing behaviors to detect ethanol by morphological variation of layers are discussed in detail. This research was partially supported by Agency for Defense Development (ADD) as global corporative research for direct urine fuel cell and Auburn University IGP. Figure Caption Fig. 1 XRD patterns of synthesized (a) as-precipitated Ni(OH)2 and (b) calcined NiO at 300 °C for 1 hr and 3 hr. Fig. 2. Morphology of (a) the as-precipitated nickel hydroxide particles and calcined NiO particles at 300 °C for (b) 1 hr and (c) 3 hr. Refernce 1. Zhang, Q., P. Wang, J. Li, and X. Gao, Biosens. Bioelectron., 15[5](2000)249-256. 2. Moorhead, K.T., D. Lee, J.G. Chase, A. Moot, K. Ledingham, J. Scotter, R. Allardyce, S. Senthilmohan, and Z. Endre, Computer methods and programs in biomedicine, 89[3](2008)226-238. 3. de Lacy Costello, B., R. Ewen, N.M. Ratcliffe, and M. Richards, J. Breath Res., 2[3](2008)037017. 4. Ahn, H., J.H. Noh, S.-B. Kim, R.A. Overfelt, Y.S. Yoon, and D.-J. Kim, Mater. Chem. Phys., 124[1](2010)563-568. 5. Ahn, H., J.-H. Park, S.-B. Kim, S.H. Jee, Y.S. Yoon, and D.-J. Kim, Electrochem. Solid-State Lett., 13[11](2010)J125-J128. 6. Dirksen, J.A., K. Duval, and T.A. Ring, Sensors and Actuators B: Chemical, 80[2](2001)106-115. 7. Meher, S.K., P. Justin, and G.R. Rao, Nanoscale, 3[2](2011)683-692. Figure 1

Stable Solar-Driven Water Oxidation to O2(g) by Ni-Oxide-Coated Silicon Photoanodes.

Semiconductors with small band gaps (<2 eV) must be stabilized against corrosion or passivation in aqueous electrolytes before such materials can be used as photoelectrodes to directly produce fuels from sunlight. In addition, incorporation of electrocatalysts on the surface of photoelectrodes is required for efficient oxidation of H2O to O2(g) and reduction of H2O or H2O and CO2 to fuels. We report herein the stabilization of np(+)-Si(100) and n-Si(111) photoanodes for over 1200 h of continuous light-driven evolution of O2(g) in 1.0 M KOH(aq) by an earth-abundant, optically transparent, electrocatalytic, stable, conducting nickel oxide layer. Under simulated solar illumination and with optimized index-matching for proper antireflection, NiOx-coated np(+)-Si(100) photoanodes produced photocurrent-onset potentials of -180 ± 20 mV referenced to the equilibrium potential for evolution of O2(g), photocurrent densities of 29 ± 1.8 mA cm(-2) at the equilibrium potential for evolution of O2(g), and a solar-to-O2(g) conversion figure-of-merit of 2.1%.