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Current developments and challenges in energy-efficient windows for building integration relate to the design and realization of high-performance, durable electrochromic devices and semitransparent...

Photovoltachromic devices combine photovoltaic and electrochromic behaviours to enable adjustable transparency glazing, where the photovoltaic component supplies the power to drive the coloration. Such stand-alone, self-powered devices are of commercial interest for integration into windows and surfaces of buildings and vehicles. Here, we report for the first time a perovskite-based photovoltachromic device with self-adaptive transparency. This multifunctional device is capable of producing electrical power by solar energy conversion as well as undergoing a chromic transition from neutral-color semi-transparent to dark blue-tinted when irradiated with solar light, without any additional external bias. The combination of semi-transparent perovskite photovoltaic and solid-state electrochromic cells enables fully solid-state photovoltachromic devices with 26% (or 16%) average visible transmittance and 3.7% (or 5.5%) maximum light power conversion efficiency. Upon activating the self-tinting, the average visible transmittance drops to 8.4% (or 5.5%). These results represent a significant step towards the commercialization of photovoltachromic building envelopes.

Herein, we present, for the first time, the features of a full solid-state electrochromic (EC) device fabricated on a single substrate, made of glass as well as flexible plastic, adopting a low-cost, eco-friendly, and facile fabrication process. By combining a solution processing of Nafion electrolyte film and RF sputtering deposition at room temperature (RT) on Nafion, we obtained monolithic systems with a simplified architecture (substrate/ITO/WO3/Nafion/ITO) in which a suitable Nafion film (8 µm thick) tightly shares its interfaces with the WO3 layer and the highly transparent and conductive RF-sputtered ITO film. Compared to conventional sandwich-type EC devices using semi-solid or liquid electrolytes, the resulting devices exhibited a strong enhancement in terms of interface properties, robustness, cyclic stability, and long-term durability (at least 1000 chronoamperometric cycles). Moreover, electro-optical characterizations highlighted high transmittance modulation (49% at 650 nm), astonishing results in terms of coloration efficiency (139 cm2/C), and low energy absorption (80 mW s/cm2).

Electrochromic devices (ECDs) represent one of the most promising energy saving and solar control technology for the market of energy-efficient building and optoelectronic devices. A continuous and intense effort is currently devoted to the development of effective solid-state ECDs and their integration in multifunctional systems, such as photoelectrochromics. Here, the fabrication of simplified all-solid-state WO3 based ECDs on single-substrate is reported, demonstrating how the rational design of highly interconnected WO3 columnar nanostructures with Nafion polymer matrix remarkably decreases the charge transport barrier at the hybrid electrolyte/electrochromic interface (EEI), thus determining an impressive improvement of overall device performances. The soft polymer substrate of the electrolyte plays a key role on the formation of WO3 pillar-like structures and on the increase of interfacial contact area by affecting the vacuum-deposition WO3 growth. Apart from providing higher transmittance in bleached state, the resulting device, entirely manufactured at room temperature by bottom-up process, exhibits lower activation voltages (0.5–3 V) and faster switching kinetics (5–10 s) compared with monolithic ECDs based on both bulk and mesoporous WO3 films. Furthermore, the enhanced EEI enables the scale-up on large area and flexible substrate ensuring simultaneously a wide optical contrast (ΔT = 70%), and high coloration efficiency.

The design and development of effective solid-state electrolytes represent an emerging challenge towards the fabrication of electrochromic (EC) and multifunctional devices, such as photoelectrochromics, with benefits in terms of reduced cost, environmental impact as well as safety. Here, we present the processing and the characterization of a suitable Nafion film with the certain thickness of 8 μm used as electrolyte layer in a novel solid-state EC device fabricated at room temperature (RT) on a single substrate (both glass and plastics) with an architecture based on a substrate/ITO/WO3/Nafion-film/ITO configuration. In particular, we focused on the morphological characteristics, proton conductivity and water molecular dynamics of Nafion film in order to provide insight into the EC behavior of these novel devices. EIS analysis performed over a wide range of RH and temperature, showed good proton conductivity values (e.g. 4.42 × 10− 3 S cm− 1 at 30 °C and 50% RH), suitable for practical EC operation. At the same time, high values of water self-diffusion coefficients (D) and the spin-lattice relaxation times (T1) were measured by NMR spectroscopy, proving a similar behavior as well as the same proton conduction mechanism with that observed for thicker Nafion membrane (50 μm thick) prepared by solution casting. These findings were confirmed by the water uptake measurements since both the film and the membrane showed a water uptake value of about 24 wt%. Furthermore, a homogenous, uniform and very smooth surface (Ra of 0.94 nm) with small grain size (ca. 50 nm) was observed by SEM and AFM analysis. Noteworthy, the Nafion film ensured high optical properties, interfacial robustness and electrochemical stability to EC device: cyclability (300 CV cycles), long-term durability of at least 1000 chronoamperometric cycles.

The integration of energy-saving electrochromic systems with novel functions and features in a single smart multifunctional device promises to achieve remarkable technological advancements for a wide range of consumer products showing more versatility, responsivity to different external inputs, and ability to operate in interactive modes. Here, we report a novel architecture in which a solid-state electrochromic cell and a solid-state organic light emitting diode are fully integrated in a single, highly transparent, solid-state electrochromic OLED device. This multifunctional device is capable of tuning its optical properties such as transmittance (chromic transition) and of producing light by electroluminescence, simultaneously or independently. The rational design of the solid-state electrochromic cell and the highly transparent OLED enables the construction of the integrated device in a monolithic unit. In such a structure the photonic architecture of the OLED device not only guarantees high transmittance, but, operating synergically with the electrochromic component, it outperforms the optical properties and electrochromic responses by the interference phenomenon, achieveing an optical contrast of 57% (ΔTbleaching/colouring @ 650 nm), and a coloration efficiency of 169 cm2 C−1, with very low energy consumption (80 mW cm−2). The OLED component exhibits luminance above the minimum values required for display and lighting applications, which are 300 cd m−2 and above 800 cd m−2, respectively. This result represents a further step towards the development of next-generation multifunctional EC devices such as full solid-state photoelectrochromic devices, and, importantly, this can open the way for new electrochromic “smart” window systems such as retail display windows or display EC glasses for augmented reality.

FePt nanoparticles, containing a near-equal atomic percentage of Fe and Pt, with a face centered tetragonal structure ( fct ), are challenging for potential applications in high performance permanent magnets and high density data storage. In this study, we report on the chemical synthesis, carried out both solvothermally and hydrothermally in autoclave reacting iron (III) acetylacetonate and platinum (II) acetylacetonate with tri- or tetra-ethylene glycol, these employed as solvents, reducers and particle surface protecting agents as well. In both methods, a subsequent thermal treatment at high temperatures is necessary to transform the magnetic soft face centered cubic ( fcc ) phase to the hard fct one. Organic low-weight molecules, generally used to protect the nanoparticle surface and avoid particle aggregation, are decomposed by the thermal treatment resulting in particle aggregation and coalescence phenomena; on the contrary, in this case, a polymer matrix is formed as particle protecting agent and, by thermally treating the hydrothermally prepared nanoparticles up to 750 °C for 1 h, the pure magnetic hard fct phase is obtained while preserving the nanostructure. A detailed study is carried out on FePt nanoparticle structure ( fcc and fct phases) and correlated to the magnetic properties of the system.

Poly(o-methoxyaniline) and poly(o-methylaniline) were synthesized by oxidative polymerization in the presence of multi-walled carbon nanotubes (MWNT) for the fabrication of chloroform processable nanocomposites obtained by embedding MWNT in the polymer matrix without the formation of covalent bonds. The study of pressure–area isotherms highlighted different substituents along the aromatic rings affected the packing grade of macromolecules when spreading on different subphases in relation to the associated sterical hindrance. The presence of MWNT inside the polymer matrix showed to favor a more stretched conformation of macromolecules with a subsequent increment of area/molecule values with respect to the corresponding pure conducting polymers. Furthermore, the sterical hindrance affected the nanocomposite electrochemical properties and conducting polymers containing less hindering substituents along the aromatic rings turned out to be faster electrochemical systems. Less hindering substituents were also able to enhance the conducting properties of nanocomposite materials in association with MWNT.

The properties of diamond-like carbon (DLC) are strongly affected by the amount of carbon atoms bonded in sp 2 and sp 3 electronic hybridizations. Also the amount of incorporated hydrogen and oxygen plays an important role in the final properties of DLC films. Usually, the structure and chemical composition of thin DLC films can be changed by varying the deposition parameters. Therefore, the influence of PECVD process parameters on the properties of DLC films, grown on Si substrates, was investigated in this work. Thin DLC films were deposited in a CH 4 /H 2 plasma by using Ar as a gas carrier. Different ratios of gas flows were used as a variable parameter of the PECVD process. The effect of cathodic ion bombardment was also investigated. The chemical composition of DLC specimens was studied by X-ray photoelectron spectroscopy (XPS). The ratio of carbon in sp 2 and sp 3 hybridizations was determined by analyzing the first derivative of Auger C KLL spectra. These results were also confirmed by the measurements of electrical resistivity. The changes of surface morphology and microadhesion were analyzed by Atomic Force Microscopy (AFM).

The aim of this study was to perform a surface morphology assessment with nanometer scale resolution on femoral heads made of an advanced zirconia toughened alumina (ZTA) composite. Femoral heads were characterized to a degree of statistical accuracy in the as-received state and after exposures up to 100 h in severe vapor-moist environment. Surface screening was made using an atomic force microscope (AFM). Scanning was systematically repeated on portions of surface as large as several tens of micrometers, randomly selected on the head surface, to achieve sufficient statistical reliability without lowering the nanometer-scale spatial resolution of the roughness measurement. No significant difference was found in the recorded values of surface roughness after environmental exposure (at 134°C, under 2 bar), which was always comparable to that of the as-received head. Surface roughness safely lay