Protecting Perovskite Solar Cells against Moisture-Induced Degradation with Sputtered Inorganic Barrier Layers
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
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Barrier layer design reduces top electrode ion migration in perovskite solar cells
We report on an examination of mobile ion concentration ( N 0 ) in perovskite solar cells (PSCs) as a function of temperature and device architecture.
Penukula, Saivineeth [Renewable Energy Materials a↗
Fabrication of stable electrode/diffusion barrier layers for thermoelectric filled skutterudite devices
Disclosed are methods for the manufacture of n-type and p-type filled skutterudite thermoelectric legs of an electrical contact. A first material of CoSi2 and a dopant are ball-milled to form a first powder which is thermo-mechanically processed with a second powder of n-type skutterudite to form a n-type skutterudite layer disposed between a first layer and a third layer of the doped-CoSi2. In addition, a plurality of components such as iron, and nickel, and at least one of cobalt or chromium are ball-milled form a first powder that is thermo-mechanically processed with a p-type skutterudite layer to form a p-type skutterudite layer “second layer” disposed between a first and a third layer of the first powder. The specific contact resistance between the first layer and the skutterudite layer for both the n-type and the p-type skutterudites subsequent to hot-pressing is less than about 10.0 μΩ·cm2.
Jie, Qing↗
Storing molecule within porous materials with a surface molecular barrier layer
In some aspects, the present disclosure provides compositions comprising a nanoporous material such as a metal organic framework and an amine containing compound. In some aspects, these compositions may be used to improve the affinity of a guest molecule to the nanoporous material relative a nanoporous material which had not been treated with the amine containing compound.
Tan, Kui↗
Interfacial Zirconate Formation Influenced by the Porosity of Sm-doped Ceria Barrier Layers
23rd International Conference on Solid State Ionics (SSI-23), Boston, MA, July 17-22, 2022
Picard, Yoosuf↗
Friction Stir Processed Repair Welding of Dry Storage Canisters and Mitigation Strategies: Effect of Engineered Barrier Layer on Environmental Degradation
The proposed project aims to develop a friction sir based repair technique to heal cracks of stainless steel dry storage canisters (DSCs), created by the effect of stress corrosion cracking (SCC). In real service conditions, the welded parts of the canisters become prone to SCC under exposure to aggressive chemical environment. The focus of the project is on developing a mitigation strategy that can be implemented for countering SCC in DSCs following a two-pronged approach: (i) apply friction stir processing (FSP) as a crack repair technique while creating compressive residual stresses at the canister material surface, thus improving resistance against SCC; (ii) add molybdenum and/or nitrogen by friction stir based alloying process to create compositions that improve pitting resistance and thus enhance resistance against SCC. The specific project objectives are listed below: • Investigate FSW of 304L SS a potential repair welding technique of dry storage canisters; • Optimize the FSW parameters to introduce surface compressive stress profiles in the weldments; • Develop a FSP method to surface alloy the 304L with nitrogen and Mo by adding CrN and Mo powders; • Evaluate the surface compressive residual stress profile during FSW and FSP processes; • Evaluate the localized corrosion resistance of the FSW and FSP samples as a function of temperature, chloride concentration, and surface alloy composition; • Evaluate the SCC behavior of the FSW and FSP samples as a function of stress, chloride concentration, and temperature at different surface chemistries and induced residual stress profiles.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Chapter 3: Ultrathin Oxides for Solar Cells
This chapter discusses the many uses of ultrathin oxide layers across a broad range of photovoltaic (PV) technologies. The chapter is broken down into six sections, working from the solar absorber outwards: passivation layers, selective contact/buffer layers, recombination layers, barrier layers, anti-reflective coatings, and anti-soiling layers. The goal is to introduce the layer function, outline the scientific mechanisms behind each function, and provide illustrative examples from academic literature and industry. One theme in this chapter is the multifunctionality of oxide layers in the PV device stack, that is, a single layer rarely has only one purpose and therefore certain ideas will build upon other sections. The chapter covers a wide range of material and the discussions and examples are by no means exhaustive. The best efforts have been made to capture the central concepts for each topic and direct the reader to additional resources that have been found by the authors to be useful and relevant.
anti-reflection coatings↗
Selective Isolation of Surface Grain Boundaries by Oxide Dielectrics Improves Cd(Se,Te) Device Performance
Cd(Se,Te) photovoltaics (PV) are the most widely deployed thin-film solar technology globally, yet continued efficiency improvements are stymied by challenges at the device hole contacts. The inclusion of solution-processed oxide layers such as AlGaO x in the contact stack has yielded improved device open-circuit voltages (V OC ) and fill factors (FF). However, contradictory mechanisms by which these layers improve the device properties have been proposed by the research community. We demonstrate in this work that an underappreciated property of such spin-coated layers is the preferential deposition at grain boundaries, a process that isolates the grain boundaries during contact metallization. The effects of grain-boundary isolation are probed by varying the coverage of solution-processed AlGaO x “barrier” layers on the Cd(Se,Te) surface, quantified by scanning Auger microscopy. Examining coverage-dependent V OC and FF, it was observed that isolating the grain boundaries during metallization is sufficient to prevent damage to the absorber that occurs in devices lacking a barrier layer, while additional coverage contributes to the increased series resistance. Such an effect is agnostic to the material used as a barrier layer, as long as the material does not itself damage the absorber. Spin-coated SiO x was used in place of AlGaO x for an equally beneficial effect. This grain-boundary isolation phenomenon is also observed during Mo deposition and in absorbers that have been contacted with a nitrogen-doped ZnTe layer. The mechanisms by which metallization may degrade the absorber are discussed, as are contact design strategies leveraging barrier layers, which may lead to improved device efficiencies.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
SPUTTERED THIN FILMS FOR VERY HIGH POWER, EFFICIENT, AND LOW-COST COMMERCIAL SOFCS
The aim of this project was to leverage the low area specific resistance (ASR) of Redox’s GDC electrolyte-based cell architecture and increase solid oxide fuel cell (SOFC) efficiency (i.e., open circuit voltage, or OCV) without significantly increasing cell resistance. The key to achieving the increased SOFC efficiency is the introduction of a thin sputtered yttria stabilized zirconia (YSZ) electron-blocking layer and a thin sputtered gadolinia doped ceria (GDC) barrier layer on top of the half-cell substrate (i.e., anode and GDC electrolyte). A key initial effort of the project was to improve the quality of the half-cell substrate surface so that any remaining defects were significantly smaller than the desired film thickness. During lab-scale trials, we had to overcome challenges with film cracking during post-sputtering treatments (e.g., thermal anneals) as well as damage to the sputtering targets. After the initial lab-scale trials, the focus shifted toward the use of commercial scale sputtering equipment with a sputtering equipment manufacturer in the microelectronics industry. Using the commercial sputtering equipment, we deposited films with different variations of power, PO2, sputtering time, platen speed, etc. We then determined the combinations of sputtering conditions and post-sputtering treatments that yielded high-quality films without cracks or other significant defects. While thin films were deposited on cells as large as 10 cm by 10 cm, the processing was optimized using 4 cm by 4 cm cells. Cell performance was evaluated in stainless-steel test fixtures between 500 °C and 700 °C with hydrogen fuel fed to the anode and air fed to the cathode. Extensive studies allowed us to determine that modified cathode and cathode contact firing processes were required to achieve theoretical OCV. Moreover, use of the new firing processes resulted in the need for a modified cathode contact to achieve a low ASR. In summary, the project demonstrated the performance of high OCV (1.13 V at 650 °C) from sputtered layers and a low ASR (~0.25 Ohms-cm2 at 650 °C) resulting from a modification of cathode/contact processing and the introduction of alternative contact layers that are sufficient to yield a Gen-1 cell with a maximum power density of approximately 1.2 W/cm2. At an operating voltage of 0.74 V, this would yield a cell power density of ~1.1 W/cm2. While not utilized in this project, a Redox Gen-2 cell has a catalyst-infiltrated porous anode that reduces the ASR by more than 50% from that of the Gen-1 cells used in this project. Therefore, if the sputtered YSZ electron-blocking layer and GDC barrier layer are added to a Gen-2 half cell with a similar increase in OCV to the theoretical value of ~1.13 V at 650 °C, and if the same improvement in ASR (from that demonstrated in this project) is achieved when using the Gen-2 half-cell architecture as a sputtered cell substrate, then the power density at 0.74 Vop could be as high as ~2.6 W/cm2. The impact of such power density gains, while still maintaining high cell efficiency, and thus high system efficiency, is a dramatic decrease in system cost because the stack represents ~30-40% of the SOFC system cost.
01 COAL, LIGNITE, AND PEAT↗
Method for forming a nitrogenation barrier and machine formed using a body having the nitrogenation barrier
A method includes forming one or more oxide barrier layers on one or more protected portions of a magnetic, metallic body, and converting one or more unprotected portions of the magnetic, metallic body to a less magnetic material by exposing the magnetic metallic body having the one or more oxide barrier layers formed thereon to nitrogen. One or more protected portions of the magnetic, metallic body that are beneath the one or more oxide barrier layers are not converted to the less magnetic material. The method can be used to form one or more layers of a laminated electric motor.
36 MATERIALS SCIENCE↗
Regrowth method for fabricating wide-bandgap transistors, and devices made thereby
Methods are provided for fabricating a HEMT (high-electron-mobility transistor) that involve sequential epitaxial growth of III-nitride channel and barrier layers, followed by epitaxial regrowth of further III-nitride material through a window in a mask layer. The regrowth takes place on the barrier layer, only in the access region or regions. Devices made according to the disclosed methods are also provided.
36 MATERIALS SCIENCE↗
Insulated exhaust port liner for a cylinder head assembly of a motor vehicle
An insulated exhaust port liner of a cylinder head assembly for fluidly connecting to an internal combustion engine of a motor vehicle includes a sealing layer. The sealing layer has a first surface defining a passage for fluidly connecting to the internal combustion engine and receiving exhaust gas. The sealing layer further includes a second surface opposite to the first surface. The liner further includes a thermal barrier layer coated onto the second surface of the sealing layer. The thermal barrier layer is a porous non-woven material for supporting the sealing layer on the cylinder head and reducing a transfer of heat from the sealing layer to the cylinder head.
Andruskiewicz, IV, Peter P.↗
Development of Stable Solid Oxide Electrolysis Cells for Low-Cost Hydrogen Production
The project objective was to demonstrate a solid oxide cell-based steam electrolysis stack that exhibits robustness, reliability, endurance, hydrogen purity, and produces hydrogen at elevated pressure of 2 to 3 bar. Innovative materials and processing methods were evaluated to improve degradation characteristics. Performance improvement focused on nearly all layers involved in the cell and stack assembly. Primary attention was paid to zirconia-ceria interface resistance control via sintering optimization and decrease in degradation from the oxygen electrode by evaluating low strontium (Sr) or Sr-free composition for both the oxygen electrode and current collection layer. Stack robustness was addressed by validating redox tolerance of fuel electrode, confirming capability of cells to survive repeated thermal cycles, studying the effect of pressure on performance and degradation, evaluating the effect of contamination on fuel and oxygen electrode performance and degradation, and identifying mitigation strategies to improve performance. The characterization included evaluation of electrochemical performance and stability followed by microstructural analysis. At the cell level, performance and stability improvements were achieved by incorporating a Sr-free oxygen electrode and a denser oxygen electrode barrier layer. At the stack level, pressurized operation reduces demand on first stage compression, the redox tolerant fuel electrode mitigates risk from service interruptions, and improvements to interconnect coating alleviate chromium (Cr) contamination effects. The denser barrier layer was achieved by adding a sintering aid to the samaria-doped ceria (SDC) composition that reduced sintering temperature by 150 °C. The resulting density was on par with the baseline SDC barrier layer density and the lower sintering temperature resulted in less resistive phase formation during sintering. Button cell tests did not demonstrate a change in performance when exposed to silicon (Si) or manganese (Mn) impurities to the fuel electrode and Cr impurity to the oxygen electrode. More detailed study however is warranted. The project addressed SOEC performance and stability at the cell and stack levels through a systematic approach to known sources of degradation that were combined and tested in three stack tests using an electrolyte supported cell design to allow for evaluation of a variety of fuel and oxygen electrode compositions. STK-82 and STK-83 had identical compositions. STK-100 incorporated the best materials and processing variables developed under this and concurrent projects, and was tested at elevated pressure in steam electrolysis. • STK-82 recovered performance after redox and thermal cycling, demonstrating the robustness of the stack and seals. It exhibited stable performance in testing for 500 hours in SOEC mode, followed by 300 hours of cycling between SOEC and SOFC tests. Degradation during SOEC operation was 1.8 %/ 1,000 hours. • STK-83 generated hydrogen at >80% steam conversion, and oxygen above 98.5 % purity during pressurized operation. Both hydrogen and oxygen were generated at 3 barg pressure without the use of a pressure vessel. In addition to balanced pressure, electrolysis operation at 1 bar differential pressure across anode and cathode was also demonstrated to substantial the robustness of the cell and seal. • STK-100 measured at initial ambient pressure conditions showed an area specific resistance of 1.1 ohm-cm 2 , and STK-83 had 1.3 ohm-cm 2 .
08 HYDROGEN↗
AlGaInAs/InP semiconductor lasers with an ultra-narrow waveguide and an increased electron barrier
Semiconductor lasers based on AlGaInAs/InP heterostructures with an ultra-narrow waveguide and an increased electron barrier layer are developed. It is shown that the use of this waveguide in conjunction with profiled doping ensures a balance between internal optical losses and heat resistance. Additional use of strained wide-bandgap layers as blocking barriers limiting electron leakage from the active region makes it possible to increase the output power at the same pump current. The developed lasers with a stripe contact 100 μm wide demonstrate at room temperature an output optical power of 4.0 – 4.4 W (pump current 14 A) in a continuous-wave regime and 15 – 17 W (100 A) in a pulsed regime (100 ns, 1 kHz) at wavelengths of 1450 – 1500 nm. (paper)
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Electron transport through antiferromagnetic spin textures and skyrmions in a magnetic tunnel junction
An ideal layered $\hat{x}$-polarized antiferromagnet (AFM) between two antialigned $±\hat{z}$ polarized ferromagnetic (FM) contacts transmits no current due to a π phase difference of the matrix elements coupling the spin degenerate states to the two FM contacts. Inserting a normal-metal layer or tunnel barrier layer between one FM contact and the AFM alters this phase difference, and due to the unequal weighting of the two spins at the interface, it also breaks the spin degeneracy of the two AFM states. Further, the broken symmetry of the matrix elements combined with the broken degeneracy of the AFM states results in a Fano resonance in the transmission and a turn-on of the $T_{↑,↓}$ transmission channel. Such a magnetic tunnel junction geometry with two antialigned $±\hat{z}$ FM contacts can electrically detect an AFM skyrmion. The AFM skyrmion serves as an analog of the oblique polarizer in the triple-polarizer experiment. Resistances and resistance ratios are calculated and compared for FM and AFM skyrmions in a magnetic tunnel junction.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Accelerated Scaling to Rapid Open-Air Fabrication of Durable Perovskite Solar Modules
The goals of this SETO project (DE-EE0008559, Accelerated Scaling to Rapid Open-Air Fabrication of Durable Perovskite Solar modules) are to address the principal challenges towards the successful commercialization of perovskite solar modules utilizing scalable, high-throughput open-air spray deposition. The successful outcome of the project will provide the foundation of an all open-air spray deposited perovskite solar module with hole transport layer (HTL), perovskite, electron transport layer (ETL), and barrier layer development while establishing a fundamental understanding of perovskite device behavior under accelerated aging conditions. Through this program, we have made significant progress towards a commercializable pathway for perovskites. (1) We’ve demonstrated the successful open-air deposition of perovskite and transport layer materials. These deposition methods were chosen for their inherent scalability, and open-air processing enables a significant reduction in processing costs. These methods are also compatible with high throughputs, demonstrating the fastest perovskite film deposition at these performance levels. (2) Development of a unique all-fiber laser scribing procedure provides a high-performance, low-cost method for further improvements in scalability. (3) Our group has also placed a unique emphasis on device stability. The development of testing standards for perovskite modules is required to thoroughly evaluate potential candidates for commercialization, and we’ve taken inspiration from current industry standards to provide an honest insight into the performance and reliability of our devices. (4) An extensive cost model detailing the specific contributions of each device layer and production component provides the most thorough evaluation of any perovskite technology against conventional silicon and compound semiconductor solar devices. The cost model is a critical advancement that will provide the foundation for evaluating the levelized cost of energy (LCOE) of this technology.
14 SOLAR ENERGY↗
Self-healing barrier films for vacuum insulation panels
A self-healing vacuum insulation panel and a method of manufacture are provided. The vacuum insulation panel includes a self-healing, multi-layer barrier film including a separator between a curing agent and a curable resin. Upon damage to the separator, the curing agent penetrates the separator due to a pressure differential across the barrier film and reacts with the curable resin to seal any cuts or punctures. The curing agent and the curable resin can be selected to have long term stability and a short reaction time with no need for external stimuli. As a result, the multi-layer barrier film can retain the internal vacuum and maintain a desirably low thermal conductivity using low-cost, commercially available epoxies and curing agents.
Biswas, Kaushik↗
High-temperature and/or high pressure gas enclosure
A gas enclosure can include a refractory metal liner; a ceramic matrix composite cladding; and a diffusion barrier layer. The refractory metal liner is adapted to surround and enclose a gas to be contained within the gas enclosure. The diffusion barrier layer is disposed between the refractory metal liner and the ceramic matrix composite cladding.
Miao, Yinbin↗