No description available.

This thesis is a comparative study of nickel oxide based thin films for use as a counter electrode in a variable transmittance electrochromic device. Coatings have been prepared using anodic electrodeposition, colloidal precipitation and radio frequency (r.f.) sputtering. Systematic studies of the effect of deposition process parameters on optical and electrochromic properties of such films have been undertaken. Optimum conditions for the deposition of coatings deposited by colloidal and anodic deposition have been determined. A novel process for the colloidal deposition of electrochromic a-Ni(OH)2 coatings using a simple one dip process is reported. Also the electrochromic properties of coatings anodically deposited from aqueous solutions containing NiS04 and NH40H were improved by the addition of the non-ionic surfactant polyoxyethylene sorbitan monolaurate. Spectroscopic and electrochemical analytical techniques were used to identify the chemical composition of the coloured and bleached states. It was found using Fourier transform infra-red spectrophotometry (FTIR) that coatings deposited by anodic and colloidal deposition contained f3-Ni(OH)2 and a-Ni(OH)2 respectively in the as-deposited and transparent states. For coatings deposited by both techniques 13 or y-NiOOH was detected in the coloured state using FTIR. Using Raman spectroscopy, y-NiOOH was detected in the coloured state for coatings deposited by anodic deposition from solutions containing the additive polyoxyethylene sorbitan monolaurate. I3-Ni(OH)2 was also detected in the transparent state of r.f. sputtered coatings that were electrochemically cycled in 1M KOH(aq). Using cyclic voltammetry the oxidation of nickel hydroxide to the oxyhydroxide was detected during colouration for coatings produced using anodic electrodeposition, colloidal precipitation and r.f. sputtering (after cycling sputtered films for 1 hour in 1M KOH(aq)). This information has been compared for films prepared using the different deposition techniques to enable the respective colouration mechanisms to be elucidated. Prototype electrochromic devices have been constructed and their performances assessed. It can be concluded that nickel oxide based coatings can be used as suitable counter electrodes for hydrated electrochromic devices.

The building sector is a one of modern society’s biggest users of energy. In turn, a building’s windows have a significant impact on its energy usage. Electrochromic windows have a thin film on one of the panes, designed to variably change the tint of the window. Thereby the solar heat gain, needed internal lighting and building energy utilization are varied. This thesis uses the simulation software IDA ICE 4.5 to simulate control scenarios for electrochromic windows. The goal is to examine how well this software can simulate the windows as well as to explore the potential of creating custom control algorithms for the windows. The impact of the control scenarios on the energy consumption of a building is then analyzed. The reference case for the simulations is a regular window with blinds, where the blinds are controlled with a built-in algorithm. The simulated control scenarios for the electrochromic windows were; the built-in algorithm, always off, always on, operative temperature, workplane illuminance, and light levels at the façade and window. In the simulation results the energy usage was slightly lowered with the electrochromic windows using the built-in control compared to the reference case. The custom algorithm that uses the light levels at the façade and window was designed to improve upon the built-in algorithm with additional adjustable settings. However, this custom algorithm produced similar results to the built-in algorithm and the majority of the additional settings had little impact on the energy usage. The other custom designed algorithms measured workplane illuminance and operative temperature to control the shading. These showed an overall decrease in the energy usage compared to the reference case. The IDA ICE software has potential for further simulations of a building’s energy usage while using electrochromic windows. Further investigation is needed to determine if the simulation resolution is high enough to accurately depict the effect these settings might have on the energy usage.

No description available.

Electrochromic thin films can effectively regulate the visible and infrared light passing through a window, demonstrating great potential to save energy and offer a comfortable indoor environment in buildings. However, long-term durability is a big issue and the physics behind this is far from clear. This dissertation work concerns two important parts of an electrochromic window: the anodic and cathodic layers. In particular, work focusing on the anodic side develop a new Ni oxide based layers and uncover degradation dynamics in Ni oxide thin films; and work focusing on the cathodic side addresses materials rejuvenation with the aim to eliminate degradation. In the first part of this dissertation work, iridium oxide is found to be compatible with acids, bases and Li+-containing electrolytes, and an anodic layer with very superior long-term durability was developed by incorporating of small amount (7.6 at. %) of Ir into Ni oxide. This film demonstrated sustained cycle-dependent growth of charge density and electrochromic modulation even after 10,000 CV cycles. The (111) and (100) crystal facets in Ni oxide are found to possess different abilities to absorb cation and/or anion, which yields different degrees of coloration and this is very significant for the electrochromic properties. The degradation of charge capacity in Ni oxide has an inevitable rapid decay in the first hundreds of cycles, subsequently combined with a more gradual decay, which is independent of applied potential and film composition. The consistent phenomenon can be very well modeled by power-law or stretched exponential decay; however the two models are indistinguishable in the current stage. Interestingly, in both models, the power-law exponent is 0.2 ≤ p ≤ 0.8, with most of the values around 0.5, in line with normal or anomalous diffusion models. The second part of dissertation work deals with cathodic WO3 and TiO2. WO3 suffers from ion trapping induced degradation of charge capacity and optical modulation upon electrochemical cycling. This speculation is strongly supported by direct evidence from Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA). Most importantly, this ion trapping induced degradation can be eliminated by a galvanostatic de-trapping process. Significant ion-trapping takes place when x exceeds ~0.65 in LixWO3. The trapped ions are stable in the host structure, meaning that the ions cannot de-trap without external stimuli. The similar work done on TiO2 significantly complements and extends the work on the recuperation of WO3; the difference is that the trapped ions in host TiO2 seem to be less stable compared with the trapped ions in WO3.     Overall, this dissertation presents a refined conceptual framework for developing superior electrochromic windows in energy efficient buildings.

The building sector is one of the largest consumers of energy, where the cooling of buildings accounts for a large portion of the total energy consumption. Electrochromic (EC) smart windows have a great potential for increasing indoor comfort and saving large amounts of energy for buildings. An EC device can be viewed as a thin-film electrical battery whose charging state is manifested in optical absorption, i.e. the optical absorption increases with increased state-of-charge (SOC) and decreases with decreased state-of-charge. It is the EC technology's unique ability to control the absorption (transmittance) of solar energy and visible light in windows with small energy effort that can reduce buildings' cooling needs. Today, the EC technology is used to produce small windows and car rearview mirrors, and to reach the construction market it is crucial to be able to produce large area EC devices with satisfactory performance. A challenge with up-scaling is to design the EC device system with a rapid and uniform coloration (charging) and bleaching (discharging). In addition, up-scaling the EC technology is a large economic risk due to its expensive production equipment, thus making the choice of EC material and system extremely critical. Although this is a well-known issue, little work has been done to address and solve these problems. This thesis introduces a cost-efficient methodology, validated with experimental data, capable of predicting and optimizing EC device systems' performance in large area applications, such as EC smart windows. This methodology consists of an experimental set-up, experimental procedures and a twodimensional current distribution model. The experimental set-up, based on camera vision, is used in performing experimental procedures to develop and validate the model and methodology. The two-dimensional current distribution model takes secondary current distribution with charge transfer resistance, ohmic and time-dependent effects into account. Model simulations are done by numerically solving the model's differential equations using a finite element method. The methodology is validated with large area experiments. To show the advantage of using a well-functioning current distribution model as a design tool, some EC window size coloration and bleaching predictions are also included. These predictions show that the transparent conductor resistance greatly affects the performance of EC smart windows. / Byggnadssektorn är en av de största energiförbrukarna, där kylningen av byggnader står för en stor del av den totala energikonsumtionen. Elektrokroma (EC) smarta fönster har en stor potential för att öka inomhuskomforten och spara stora mängder energi för byggnader. Ett elektrokromt fönster kan ses som ett tunnfilmsbatteri vars laddningsnivå yttrar sig i dess optiska absorption, d.v.s. den optiska absorptionen ökar med ökad laddningsnivå och vice versa. Det är EC-teknologins unika egenskaper att kunna kontrollera absorptionen (transmittansen) av solenergi och synligt ljus i fönster med liten energiinsats som kan minska byggnaders kylningsbehov. EC-teknologin används idag till att producera små fönster och bilbackspeglar, men för att nå byggnadsmarknaden är det nödvändigt att kunna producera stora EC-anordningar med fullgod prestanda. En välkänd utmaning med uppskalning är att utforma EC-systemet med snabb och jämn infärgning (laddning) och urblekning (urladdning), vilket även innebär att uppskalning är en stor ekonomisk risk på grund av den dyra produktionsutrustningen. Trots att detta är välkända problem har lite arbete gjorts för att lösa dessa. Denna avhandling introducerar ett kostnadseffektivt tillvägagångssätt, validerat med experimentella data, kapabelt till att förutsäga och optimera ECsystems prestanda för anordningar med stor area, såsom elektrokroma smarta fönster. Detta tillvägagångssätt består av en experimentell uppställning, experiment och en tvådimensionell strömfördelningsmodell. Den experimentella uppställningen, baserad på kamerateknik, används i de experimentella tillvägagångssätten så att modellen kan utvecklas och valideras. Den tvådimensionella strömfördelningsmodellen inkluderar sekundär strömfördelning med laddningsöverföringsmotstånd, ohmska och tidsberoende effekter. Modellsimuleringarna görs genom att numeriskt lösa en modells differentialekvationer med hjälp av en finita-element-metod. Tillvägagångssättet är validerat med experiment gjorda på stora EC anordningar. För att visa fördelarna med att använda en väl fungerande strömfördelningsmodell som ett designverktyg, har några prediktioner av infärgning och urblekning av EC-fönster inkluderats. Dessa prediktioner visar att den transparenta strömtilledarresistansen har stor påverkan på EC-fönsters prestanda.

Museums, art galleries, and historical sites house items of important cultural value. They must provide sufficient lighting to allow for the public viewing of these items, but are also responsible for conservation of them, which requires strict control of the light levels on delicate materials. Windows provide many benefits to building occupants, but for light control, museums restrict the use of daylight. Electrochromic (EC) glazing changes opacity based on electrical charge, so it is possible to vary the amount of daylight admitted through windows. EC glazing can be integrated with museum lighting through a building management system, which can modulate light levels based on a variety of inputs. The Renwick Gallery is used as a case study for the potential application of EC glazing in a museum space. Because of other requirements for the management of environmental conditions, the use of EC glazing will not show a significant reduction in energy consumption. However, the benefits of access to windows, daylight, and views justify its use. EC technology is advancing rapidly. Due to its current limitations and the logistics of application into a historic structure, the Renwick Gallery may best be served by future advancements.

No description available.

Thermochromic vanadium dioxide based materials undergo a metal-to-semiconductor transition. This ability can reduce the energy consumption in buildings with windows or glass facades, especially for passive cooling in warmer climates. In dependence on the temperature, the transmittance of the material for infrared light changes reversibly, regulating the amount of the solar heat transmitted into buildings. Although thermochromic vanadium dioxide based coatings have been extensively studied at laboratory scale, there are still fundamental challenges for industrial manufacturing. The present work aims to explore the prospects of the deposition of a tungsten-doped vanadium dioxide based coating onto ultra-thin glass in an upscaled roll-to-roll process. An existing laboratory scale layer stack design enabled the achievement of high performance using unipolar pulsed and high power impulse magnetron sputtering. For this purpose, a new oxygen control system was developed. Furthermore, the optical and structural properties of the deposited coatings were characterized, as well as the doping content, and further the potential for energy savings. A newly designed optical model allowed calculation of the dispersion relation of the layers and their electrical properties.:1 Introduction 1 2 Topic of the thesis 4 3 State of the art 6 3.1 Thermochromism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.2 Vanadium dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2.1 Crystalline Structure . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.2.2 Phase transition – Band structure . . . . . . . . . . . . . . . . . . 12 3.2.3 Literature review of thermochromic VO2 coatings . . . . . . . . . 13 3.2.4 Limitations of VO2 in smart window applications . . . . . . . . . 14 3.2.5 Using multifunctional layers . . . . . . . . . . . . . . . . . . . . . 15 3.2.6 Reducing the transition temperature . . . . . . . . . . . . . . . . 15 3.3 Magnetron sputtering of thermochromic coatings . . . . . . . . . . . . . 17 3.3.1 Sputtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.3.2 Magnetron sputtering . . . . . . . . . . . . . . . . . . . . . . . . . 21 3.3.3 Reactive magnetron sputtering . . . . . . . . . . . . . . . . . . . 22 3.3.4 Sputtering using multi-component targets . . . . . . . . . . . . . 24 3.3.5 Pulsed magnetron sputtering . . . . . . . . . . . . . . . . . . . . . 26 3.3.6 High-power impulse magnetron sputtering . . . . . . . . . . . . . 27 3.4 Layer growth and ion assistance . . . . . . . . . . . . . . . . . . . . . . . 30 3.5 Thin film optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 3.5.1 Interaction of light with surfaces . . . . . . . . . . . . . . . . . . . 34 3.5.2 Models for thin film optics . . . . . . . . . . . . . . . . . . . . . . 36 4 Methodology 39 4.1 Deposition process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.1.1 Roll-to-roll process . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.1.2 FOSA labX 330 Glass . . . . . . . . . . . . . . . . . . . . . . . . 39 4.1.3 Rotatable magnetrons . . . . . . . . . . . . . . . . . . . . . . . . 41 4.1.4 Materials used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 4.1.5 Oxygen flow controls . . . . . . . . . . . . . . . . . . . . . . . . . 43 4.1.6 Challenges of the roll-to-roll deposition process on UTG . . . . . 46 4.2 Deposition of ZrO2 multifunctional layer . . . . . . . . . . . . . . . . . . 47 4.3 Deposition of ZrO2/V1-xWxO2/ZrO2 with HiPIMS . . . . . . . . . . . . . 48 4.3.1 The investigation of the effect of oxygen partial pressure . . . . . 48 4.3.2 Deposition of thermochromic layers with optical emission spec- troscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.4 Deposition of ZrO2/V1-xWxO2/ZrO2 with unipolar pulsed magnetron sputtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.5 Coating characterisation . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 4.5.1 UV-Vis-NIR spectrophotometry . . . . . . . . . . . . . . . . . . . 51 4.5.2 Determination of the film properties with optical modelling . . . . 52 4.5.3 Scanning electron microscopy . . . . . . . . . . . . . . . . . . . . 55 4.6 Determination of the film thickness . . . . . . . . . . . . . . . . . . . . . 55 4.6.1 Resistivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4.6.2 X-ray diffraction . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 4.6.3 Atomic force microscopy . . . . . . . . . . . . . . . . . . . . . . . 58 4.6.4 Rutherford backscattering . . . . . . . . . . . . . . . . . . . . . . 59 5 Results and discussion 61 5.1 Bottom and top ZrO2 layers for thermochromic V1-xWxO2 coating . . . . 61 5.2 Process design for the deposition of thermochromic V1-xWxO2 coating with HiPIMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 5.2.1 The effect of oxygen partial pressure . . . . . . . . . . . . . . . . 70 5.2.2 Deposition of the layer system with optical emission spectroscopy 72 5.2.3 Determination of the W content in the thermochromic films . . . 80 5.2.4 Resistivity measurements and structure assumption . . . . . . . . 86 5.2.5 Dependence of the doping concentration in the target on the film thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 5.2.6 Influence of the deposition temperature on the thermochromic properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 5.2.7 Influence of the film thickness on the thermochromic properties . 90 5.3 Thermochromic V1-xWxO2 coating deposited with uPMS . . . . . . . . . 93 5.4 Comparison of HiPIMS (two-layer vs three-layer systems) and uPMS for V1-xWxO2 coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 6 Summary and outlook 101 6.1 Research goal and achievements . . . . . . . . . . . . . . . . . . . . . . . 101 6.2 Layer deposition and results overview . . . . . . . . . . . . . . . . . . . . 102 6.3 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 7 Appendix 105 8 Abbreviations 108 9 Formula symbols 109 Literature 118

Energieffektivisering börjar bli ett eftersträvande mål runtom i världen. Detta grundar sig i att energiförbrukningen för byggnader uppgår till ca 40 % globalt, en siffra som man vill få ner. Men att uppnå en energieffektiv byggnad är inte lätt. Detta kan göras på många och olika sätt. Ett av dem är att energieffektivisera fönstren, som är en byggnads svagaste punkt pga dess höga U-värde. Val av fönster är inte lätt, och det finns ett flertal alternativ att välja bland. I kalla klimat som Sverige söker man fönster med lågt U-värde och högt g-värde, samt en hög avskärmningsfaktor. I varmare länder vill man också ha ett lågt U-värde hos fönster men fokusen ligger främst på en låg avskärmningsfaktor. Syftet med uppsatsen var att hitta de mest energieffektiva fönstren, oavsett kostnad, för byggnader som befinner sig i länder med kallare klimat. Det var också av vikt att få veta lönsamheten för fönstren i fråga, därför har även kostnadsfrågor belysts. Metodvalen var informationssökning i olika databaser och litteratur samt att olika företag inom fönsterbranschen kontaktades, vilket ledde till att relevant och önskvärd information erhölls. Därefter fortskred arbetet genom kalkyleringar för energibalansen och lönsamheten. Vacuumfönster, aerogelfönster samt kromogena fönster hör till framtida fönster som kan tillföra positiva inverkan på energibalansen för byggnader. Men dessa fönster är i nuläget inte helt färdigutvecklade, fast har potential att bli världsledande. Vacuumfönster och kromogena fönster är i nuläget bättre lämpade för varmare klimat. Lyckas man komma längre med deras nutida utveckling är det inte omöjligt att anpassa de för kallare klimat. Aerogelfönster ger mest energibesparing vid byte av fönster, men pga vissa optiska egenskaper och komplicerad tillverkning av produkten är den i nuläget inte optimal vid ett fönsterbyte. De framtida fönstren är ej heller ekonomiskt försvarbara, det finns i dagsläget kommersiella energieffektiva fönster som är billigare att införskaffa och ger ett ansenligt bra resultat för en byggnads energibalans. / Energy optimization is starting to be a pursued worldwide main goal. This is based on the global energy consumption that occurs in buildings, which is about 40 percent. There is no doubt that this value needs to be lowered. But to achieve an energy efficient building is not easy. Although, this can be done in many and different ways. One of them is to optimize the windows, which is a buildings weakest point due to its high U-value.The choice of windows can be a harsh decision, there’s plenty of windows to choose among. In heating dominated climates, as the one in Sweden, it is necessary to choose windows with low U-values and high g-values, also a high solar heat gain coefficient/shading coefficient is required. A window with a low U-value is also important in cooling dominated climates but the main focus is instead on a low shading coefficient, which is not the case in this thesis. The purpose is to find the most energy efficient window that lowers the need for active heating in buildings, and also reveal and discuss the cost issues for the chosen windows.By searching in scientific databases and contacting companies active in the window industry the desired information was obtained. Calculations including the energy balance and present value were made, which gave an indication of the profitability for the different windows. Vacuum, aerogel and chromogenic window are examples of future windows which can have a positive impact on the energy balance in buildings. Yet these windows are currently not fully developed, but have potential to be highly valuable types of windows. Vacuum and chromogenic windows are better suited for cooling dominated climates. However if the development succeed where a big progress will be made it will not be impossible to suit them for heating dominated climates too. Aerogel windows have the best impact on the energy savings when replacing windows, but due to some optical attributes and a complicated manufacturing of the product aerogel windows are currently not an optimal choice for window replacement. The future windows isn’t either economically viable. For now, there are other commercially energy efficient windows that are cheaper to purchase. They also show an acceptable good result on the energy balance for a building.