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Metal halide perovskite solar cells (MHPSCs) hold great promise related to their high efficiency and low fabrication costs, but their long-term stability under environmental conditions remains a major challenge. In this study, we demonstrate an effective protection strategy to enhance the stability of MHPSCs through the incorporation of a double passivation layer based on an adamantane-based plasma polymer (ADA) at both the electron transport layer (ETL)/perovskite and perovskite/hole transport layer (HTL) interfaces. Our results show that the implemented ADA deposition technique is compatible with delicate substrates such as perovskites thin films, as their optical, morphological and optoelectronic properties are unaltered upon ADA deposition. At the same time, it provides effective protection to the perovskite material in high humidity environments. The ADA-double passivation not only reduces the formation of mobile ionic defects that cause additional recombination, but also significantly reduces humidity-induced degradation and mitigates the photocatalytic degradation caused by TiO2 under UV exposure. Stability tests performed under 100% relative humidity and continuous AM 1.5G illumination (ISOS-L-1) show that ADA dual passivated devices retained 80% of their initial efficiency after 4000 minutes, while reference samples dropped to 30%. The enhanced performance of ADA-passivated cells is attributed to protective nature of the plasma polymer layer resulting in a preservation of photocurrent and the prevention of new recombination routes. This dual passivation strategy offers a promising route to improve the environmental stability of PSCs and extend their operational lifetime.

Acoustic waves (AW) have recently emerged as an energy-efficient ice removal procedure compatible with functional and industrial-relevant substrates. However, critical aspects at fundamental and experimental levels have yet to be disclosed to optimize their operational conditions. Identifying the processes and mechanisms by which different types of AWs induce de-icing are some of these issues. Herein, using model LiNbO3 systems and two types of interdigitated transducers, we analyze the de-icing and anti-icing efficiencies and mechanisms driven by Rayleigh surface acoustic waves (R-SAW) and Lamb waves with 120 and 510 um wavelengths, respectively. Through the experimental analysis of de-icing and active anti-icing processes and the finite element simulation of the AW generation, propagation, and interaction with small ice aggregates, we disclose that Lamb waves are more favorable than R-SAWs to induce de-icing and/or prevent the freezing of droplets. Prospects for applications of this study are supported by proof of concept experiments, including de-icing in an ice wind tunnel, demonstrating that Lamb waves can efficiently remove ice layers covering large LN substrates. Results indicate that the de-icing mechanism may differ for Lamb waves or R-SAWs and that the wavelength must be considered as an important parameter for controlling the efficiency.

The stability and reproducibility issues related to metal halide Perovskite Solar Cells (PSCs) have prevented so far from exploiting this highly efficient photovoltaic technology under rainy or even moisture conditions and in combination with drop triboelectric nanogenerators (D-TENGs). Protecting the PSCs with a waterproof encapsulator could overcome such a disadvantage. Herein, we propose the implementation of fluorinated carbon (CFx) coatings produced by PECVD, enabling waterproof capability for the PSC and working as an energy harvesting surface for D-TENGs. These 100 nm - films present optimal optical transmittance, fully preserving the photovoltaic parameters of the cell. The improved long-term stability of the water-resistant PSCs prevents degradation under illumination in outdoor or simulated adverse environments with high humidity, high temperature, water immersion, or rain. As a remarkable result, the 50% Power Conversion Efficiency (PCE) has been retained after ten days of illumination under 100% relative humidity at 50 degrees Celsius. Also, the CFx coatings were successfully tested as a promoter agent to integrate commercial UV-curable sealants compatible with Spiro-OMeTAD, enhancing the performance stability of up to 80 % of PCE after 100 hours under illumination in a humid environment. This PSC was tested in a top-bottom electrode configuration for harvesting kinetic energy from droplets. Devices were compatible with simultaneously working as D-TENG and photovoltaic cells, yielding voltage outputs up to 12 V with maximum peak power density reaching 2.75 uW/cm2 defined by the D-TENG and PCE of 11.5 % and 8.46 mA/cm2 of short circuit current determined by the PSC under dripping and for an illumination angle of 45 degrees. The durability of the multisource device was tested under constant illumination and periodical drop impacting for more than 5 hours.

The ultimate step towards the exploitation of water as a clean and renewable energy source addresses the energies stored in the low frequencies of liquid flows, which demands flexible solutions to adapt to multiple scenarios, from raindrops to waves, including water moving in pipelines and microdevices. Thus, harvesting low-frequency flows is a young concept compared to solar and wind powers, where triboelectric nanogenerators have been revealed as the most promising relevant actors. However, despite widespread attempts by researchers, the drop energy harvesters' output power is still low, mainly because of the limitations in candidates endowed with ideal triboelectric and wetting properties and also the non-optimal and centimetre-scale device architecture that prevents the conversion of the complete kinetic energy of impinging drops. Herein, we disclose a microscale triboelectric nanogenerator that can harvest a high density of electrical power from drops through a single, submillisecond, long-lasting step. The mechanism relies on an instantaneous electrical capacitance variation owing to the high-speed contact of the drops with the electrodes' active area. We discuss the role of the precharged effect of the triboelectric surface in the time characteristic of the conversion event. The capacitive and microscale structure of the device is endowed with a small form factor that allows for the production of densely packed arrays. The proposed architecture can be adjusted to different liquids and scales and is compatible with a variety of triboelectric surfaces, including flexible, transparent, and thin-film approaches., Comment: 23 pages, 6 figures in main text, 9 figures in Supporting Information, videos available from the authors

Hybrid organometal halide perovskites (HP) present exceptional optoelectronic properties, but their poor long-term stability is a major bottleneck for their commercialization. Herein, we present a solvent-free approach to growing single-crystal organic nanowires (ONW), nanoporous metal oxide scaffolds, and HP to form a core@multishell architecture. The synthetic procedure is carried out under mild vacuum conditions employing thermal evaporation for the metal-free phthalocyanine (H2Pc) nanowires, which will be the core, plasma-enhanced chemical vapor deposition (PECVD) for the TiO2 shell, and co-evaporation of lead iodide (PbI2) and methylammonium iodide (CH3NH3I / MAI) for the CH3NH3PbI3 (MAPbI3 / MAPI) perovskite shell. We present a detailed characterization of the nanostructures by (S)-TEM and XRD, revealing a different crystallization of the hybrid perovskite depending on the template: while the growth on H2Pc nanowires induces the typical tetragonal structure of the MAPI perovskite, a low-dimensional phase (LDP) was observed on the one-dimensional TiO2 nanotubes. Such a combination yields an unprecedentedly stable photoluminescence emission over 20 hours and over 300 hours after encapsulation in polymethyl methacrylate (PMMA) under different atmospheres including N2, air, and high moisture levels. In addition, the unique one-dimensional morphology of the system, together with the high refractive index HP, allows for a strong waveguiding effect along the nanowire length.

The ability to control porosity in oxide thin films is one of the key factors that determine their properties. Despite the abundance of dry processes for the synthesis of oxide porous layers, the high porosity range is typically achieved by spin-coating-based wet chemical methods. Besides, special techniques such as supercritical drying are required to replace the pore liquid with air while maintaining the porous network. In this study, we propose a new method for the fabrication of ultra-porous titanium dioxide thin films at room or mild temperatures (T lower or equal to 120 degrees Celsius) by the sequential process involving plasma deposition and etching. These films are conformal to the substrate topography even for high-aspect-ratio substrates and show percolated porosity values above 85 percent that are comparable to advanced aerogels. The films deposited at room temperature are amorphous. However, they become partly crystalline at slightly higher temperatures presenting a distribution of anatase clusters embedded in the sponge-like structure. Surprisingly, the porous structure remains after annealing the films at 450 degrees Celsius in air, which increases the fraction of the embedded anatase nanocrystals. The films are antireflective, omniphobic, and photoactive becoming super-hydrophilic subjected to UV light irradiation The supported percolated nanoporous structure can be used as an electron-conducting electrode in perovskite solar cells. The properties of the cells depend on the aerogel film thickness reaching efficiencies close to those of commercial mesoporous anatase electrodes. This generic solvent-free synthesis is scalable and is applicable to ultra-high porous conformal oxides of different compositions with potential applications in photonics, optoelectronics, energy storage, and controlled wetting., Comment: 31 pages, 10 Figs. plus Supporting Information 7 pags, 6 figs. Full Paper

Migrating active deicing capabilities to transparent materials with low thermal conductivity has a high potential to improve the operations of several seminal industries in the automotive, robotic, energy, and aerospace sectors. However, the development of efficient and environmentally friendly deicing methods is yet in its infancy regarding their compatibility with end-user surfaces at relevant scales and real-world operations. Herein, we approach deicing through nanoscale surface activation enabled by surface acoustic waves (SAWs), allowing efficient on-demand deicing of surface areas spanning several square centimeters covered with thick layers of glace ice. We contemplate SAW-based deicing from a twofold perspective: First, we demonstrate its functionality both with a bulk piezoelectric material (LiNbO3) and a piezo-electric film (ZnO), the latter proving its versatile applicability to a large variety of functional materials with practical importance; second, we gain fundamental knowledge of the mechanisms responsible for efficient deicing using SAWs. In particular, we show that SAW vibrational modes easily transport energy over greater distances outside the electrode areas and efficiently melt large ice aggregates covering the materials' surfaces. In addition, the essential physics of SAW-based deicing is inferred from a carefully designed experimental and numerical study. We support our findings by providing macroscopic camera snapshots captured in situ inside a climate chamber during deicing and highly resolved laser-doppler vibrometer scans of the undisturbed wavefields at room temperature. Great care was taken to deposit the interdigital transducers (IDTs) used for SAW excitation only on ice-free areas close to the chip edges, leaving most of the substrate used for deicing unaltered and, as a matter of fact, demonstrating transparent deicing solutions., Comment: 15 pages including Supporting Information; 7 figures in the main text

Icing has become a hot topic both in academia and in the industry given its implications in strategic sectors such as transport, robotics, wind turbines, photovoltaics, and electricity supply. Recently proposed de-icing solutions involving the propagation of acoustic waves (AWs) at suitable substrates may open the path for a sustainable alternative to standard de-icing or anti-icing protocols. Herein we experimentally unravel some of the basic interactions that contribute to the de-icing and/or hinder the icing (ice accretion) on AW-activated substrates. The response toward icing of a model substrate system consisting of a piezoelectric LiNbO3 plate AW activated by radio-frequency (rf) signaling to planar electrodes has been characterized both at a laboratory scale and in an icing wind tunnel under forced convection conditions. Main features related to de-icing mechanisms, a decrease of ice adhesion, or the avoidance of ice accretion have been disclosed by this holistic investigation. Furthermore, additional experiments have shown that the piezoelectric substrate surfaces modified with a fluorinated ZnO thin film or a ZnO/CFx bilayer present anti-icing functionality and a synergistic response when activated with AWs. A careful analysis of the dependence of resonance frequency of the piezoelectric substrates on experimental variables such as temperature, ice formation, or wind velocity shows that this parameter can be used as an internal control procedure for real-time monitoring of icing processes onto AW-activated devices, Comment: 20 pages including Supporting Information; 8 figures in the main text

Despite the youthfulness of hybrid halide perovskite solar cells, their efficiencies are currently comparable to commercial silicon and have surpassed quantum-dots solar cells. Yet, the scalability of these devices is a challenge due to their low reproducibility and stability under environmental conditions. However, the methods reported to date to tackle such issues recurrently involve the use of solvent methods that would further complicate their transfer to industry. Herein we present a reliable alternative relaying in the implementation of an ultrathin plasma polymer as passivation interface between the electron transport material and the hybrid perovskite layer. Such nanoengineering interface provides solar devices with increased long-term stability under ambient conditions. Thus, without consideringr any additional encapsulation step, the cells retain more than 80 % of their efficiency after being exposed to the ambient atmosphere for more than 1000 h. Moreover, this plasma polymer passivation strategy significantly improves the coverage of the mesoporous scaffold by the perovskite layer, providing the solar cells with enhanced performance as well as improved reproducibility.

Polarizers are ubiquitous components in optoelectronic devices of daily use as displays, optical sensors or photographic cameras, among others. Yet the control over light polarization is an unresolved challenge as the main drawback of the current display technologies relays in significant optical losses. In such a context, organometal halide perovskites can play a decisive role given their flexible synthesis with under design optical properties . Therefore, along with their outstanding electrical properties have elevated hybrid perovskites as the material of choice in photovoltaics and optoelectronics. Among the different organometal halide perovskite nanostructures, nanowires and nanorods have lately arise as key players for the control of light polarization for lighting or detector applications. Herein, we will present the unprecedented fabrication of highly aligned and anisotropic methylammonium lead iodide (MAPI) perovskite nanowalls by Glancing Angle Deposition of PbI2 under high vacuum followed by CH3NH3I deposition at normal angle. Our approach offers a direct route for the fabrication of perovskite nanostructures virtually on any substrate, including on photovoltaic devices. The unparalleled alignment degree of the perovskite nanowalls provides the samples with strong anisotropic optical properties such as light absorption and photoluminescence, the latter with a maximum polarization ratio of P=0.43. Furthermore, the implementation of the MAPI nanowalls in photovoltaic devices provides them with a polarization-sensitive response, with a maximum photocurrent difference of 2.1 % when illuminating with the near-infrared range of the solar spectrum (>700 nm). Our facile vacuum-based approach embodies a milestone in the development of last generation polarization-sensitive perovskite-based optoelectronic devices such as lighting appliances or self-powered photodetectors., Comment: 29 Pages, 6 Figures, Supplementary Information with 4 Figures and 1 Note

The growth of amorphous TiO2 and anisotropic-polycrystalline ZnO thin-films is studied by means of coarse-grained three-dimensional kinetic Montecarlo simulations under conditions typically encountered in Plasma Enhanced Chemical Vapor Deposition experiments. The approach developed considers fluctuations in the activation energy for surface diffusion of the coarse particles that are calculated on-the-fly and depends on the mesoscale local morphological/structural landscape. The basis of this approach --which is known to work well to simulate the growth of amorphous materials using a much simpler cubic grid-- has been extended in this work to reproduce not only the morphological characteristics and scaling properties of amorphous TiO2 but also the growth of polycrystalline ZnO with a good approximation, including the evolution of the film texture and textured-grain competition during growth and its dependence on experimental conditions. The results of the simulations have been compared with available experimental data obtained by X-Ray Diffraction, analysis of the texture coefficients, Atomic Force Microscopy and Scanning Electron Microscopy, Comment: 21 first pages, including Supporting Information, 9 figures in the main text

We introduce herein the advanced application of low pressure plasma procedures for the development of piezo and triboelectric mode I hybrid nanogenerators. Thus, plasma assisted deposition and functionalization methods are presented as key enabling technologies for the nanoscale design of ZnO polycrystalline shells, the formation of conducting metallic cores in core@shell nanowires, and for the solventless surface modification of polymeric coatings and matrixes. We show how the perfluorinated chains grafting of PDMS provides a reliable approach to increase the hydrophobicity and surface charges at the same time that keeping the PDMS mechanical properties. In this way, we produce efficient Ag/ZnO convoluted piezoelectric nanogenerators supported on flexible substrates and embedded in PDMS compatible with a contact separation triboelectric architecture. Factors like crystal-line texture, ZnO thickness, nanowires aspect ratio, and surface chemical modification of the PDMS are explored to optimize the power output of the nanogenerators aimed for harvesting from low-frequency vibrations. Just by manual trigger-ing, the hybrid device can charge a microcapacitor to switch on an array of color LEDs. Outstandingly, this simple three-layer architecture allows for harvesting vibration energy in a wide bandwidth, thus, we show the performance characteristics for frequencies between 1 Hz to 50 Hz and demonstrate the successful activation of the system up to ca. 800 Hz, Comment: 17 pages, including Supporting Information Section, one Schematic, six figures

The eventual exploitation of one-dimensional nanomaterials yet needs the development of scalable, high yield, homogeneous, and environmentally friendly methods able to meet the requirements for the fabrication of under design functional nanomaterials. In this article, we demonstrate a vacuum and plasma one-reactor approach for the synthesis of the fundamental common element in solar energy and optoelectronics, i.e. the transparent conducting electrode but in the form of nanotubes and nanotrees architectures. Although the process is generic and can be used for a variety of TCOs and wide-bandgap semiconductors, we focus herein on Indium Doped Tin Oxide (ITO) as the most extended in the previous applications. This protocol combines widely applied deposition techniques such as thermal evaporation for the formation of organic nanowires serving as 1D and 3D soft templates, deposition of polycrystalline layers by magnetron sputtering, and removal of the template by simply annealing under mild vacuum conditions. The process variables are tuned to control the stoichiometry, morphology, and alignment of the ITO nanotubes and nanotrees. Four-probe characterization reveals the improved lateral connectivity of the ITO nanotrees and applied on individual nanotubes shows resistivities as low as 3.5 +/- 0.9 x 10-4 {\Omega}.cm, a value comparable to single-crystalline counterparts. The assessment of diffuse reflectance and transmittance in the UV-VIS range confirms the viability of the supported ITO nanotubes as a random optical media working as strong scattering layers. Further ability to form ITO nanotrees opens the path for practical applications as ultra-broadband absorbers in the NIR. The demonstrated low resistivity and optical properties of these ITO nanostructures open the way for their use in LEDs, IR shield, energy harvesting, nanosensors, and photoelectrochemical applications, Comment: 21 pages, 1 schematic, 6 figures, supporting information

The thin film configuration presents obvious practical advantages over the 1D implementation in energy harvesting systems such as easily manufacturing and processing and long lasting and stable devices. However, most of the ZnO-based piezoelectric nanogenerators (PENGs) reported so far relay in the exploitation of single-crystalline ZnO nanowires because their self-orientation in the c-axis and ability to accommodate long deformations resulting in a high piezoelectric performance. Herein, we show an innovative approach aiming to produce PENGs by combining polycrystalline ZnO layers fabricated at room temperature by plasma assisted deposition with supported small-molecule organic nanowires (ONWs) acting as 1D scaffold. The resulting hybrid nanostructure is formed by a single-crystalline organic nanowire conformally surrounded by a three dimensional (3D) ZnO shell that combines the mechanical properties of the organic core with the piezoelectric response of the ZnO layer. In a loop forward towards the integration of multiple functions within a single wire, we have also developed ONW@Au@ZnO nanowires including a gold shell acting as inner nanoscopic electrode. Thus, we have built and compare thin films and 3D core@shell ONW@ZnO and ONW@Au@ZnO PENGs showing output piezo-voltages up to 170 mV. The synergistic combination of functionalities in the ONW@Au@ZnO devices promotes an enhanced performance generating piezo-currents almost twenty times larger than the ONW@ZnO nanowires and superior to the thin film nanogenerators for equivalent and higher thicknesses., Comment: 18 pages, 1 Scheme, 2 Figures, 3 Figures in Supporting Information Section