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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.

Dye Sensitized Solar Cells (DSSCs) have recently regained attention for indoor light harvesting and powering wireless devices. Advantages such as cost-effectiveness, flexibility, wide angular response, and lightweight design have driven the fostering of the implementation of advanced photonic architectures, dedicated photosensitizers and compatibility with wearable carriers. However, to fully exploit their potential, crucial aspects require further attention, in particular the improvement of spectral compatibility and low-light harvesting mechanisms, as well as the development of efficient photoanodes through high-yield scalable methods. In this article, we propose the use of nanocomposite photoanodes integrating mesoporous TiO2 (m-TiO2) nanoparticles, ITO nanotubes (NTs) and TiO2 anatase shells (ITO@TiO2 NTs) prepared by step-by-step method relying on mild temperature conditions and avoiding toxic precursors. These photoanodes outperform previous attempts to implement low-dimensional ITO and ITO@TiO2 nanowires and nanotubes for outdoor light conversion, demonstrating an outstanding PCE under low artificial light intensity of 24 % for at 0.014 mWcm-2, a 166 % increase compared to the conventional architectures. Advanced microstructural, optical, and electrochemical characterizations have revealed that the strong scattering effect of the light in the visible range coupled with enhanced charge collection at low-intensity illumination are the essential mechanisms responsible for such enhanced energy conversion. Remarkably, our devices retain up to 90% of the normal incidence efficiency even under glancing illumination, while conventional reference devices show a drop down to 50%.

A well-established procedure for the photoelectrochemical (PEC) splitting of water relies on using porous electrodes of WO3 sensitized with BiVO4 as a visible scavenger photoanode semiconductor. In this work, we propose an evolved photoelectrode fabricated by a soft-template approach consisting of supported multishell nanotubes (NTs). These NTs are formed by a concentric layered structure of indium tin oxide (ITO), WO3, and BiVO4, together with a final film of cobalt phosphate (CoPi) co-catalyst. Photoelectrode manufacturing is easily implemented at large scale and combines thermal evaporation of single crystalline organic nanowires (ONWs), magnetron sputtering (for ITO and WO3), solution dripping, and electrochemical deposition processes (for BiVO4 and CoPi, respectively) plus annealing under mild conditions. The obtained NT electrodes depict a large electrochemically active surface and outperform by more than one order of magnitude the efficiency of equivalent planar-layered electrodes. A thorough electrochemical analysis of the electrodes under blue and solar light illumination demonstrates the critical role of the WO3/BiVO4 Schottky barrier heterojunction in the control of the NT electrode efficiency and its dependence on the BiVO4 outer layer thickness. Oxygen evolution reaction (OER) performance was maximized with the CoPi electrocatalyst, rendering high photocurrents under one sun illumination. The reported results demonstrate the potential of the soft-template methodology for the large area fabrication of highly efficient multishell ITO/WO3/BiVO4/CoPi NT electrodes, or other alternative combinations, for the photoelectrochemical splitting of water., Comment: Manuscript: 39 pages, 8 figures and 1 table. SI: 15 pages, 9 figures and 1 table

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

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