Scientific Papers in SCI

2015


Title: Highly Efficient Perovskite Solar Cells with Tunable Structural Color
Author(s): W. Zhang, M. Anaya, G. Lozano, M.E. Calvo, M.B. Johnston, H. Míguez, H.J. Snaith
Source: Nano Letters, 15 (2015) 1698-1702

abstract | fulltext

The performance of perovskite solar cells has been progressing over the past few years and efficiency is likely to continue to increase. However, a negative aspect for the integration of perovskite solar cells in the built environment is that the color gamut available in these materials is very limited and does not cover the green-to-blue region of the visible spectrum, which has been a big selling point for organic photovoltaics. Here, we integrate a porous photonic crystal (PC) scaffold within the photoactive layer of an opaque perovskite solar cell following a bottom-up approach employing inexpensive and scalable liquid processing techniques. The photovoltaic devices presented herein show high efficiency with tunable color across the visible spectrum. This now imbues the perovskite solar cells with highly desirable properties for cladding in the built environment and encourages design of sustainable colorful buildings and iridescent electric vehicles as future power generation sources.

March, 2015 | DOI: 10.1021/nl504349z

Title: Sonogashira Cross-Coupling and Homocoupling on a Silver Surface: Chlorobenzene and Phenylacetylene on Ag(100)
Author(s): Sanchez-Sanchez, C; Orozco, N; Holgado, JP; Beaumont, SK; Kyriakou, G; Watson, DJ; Gonzalez-Elipe, AR; Feria, L; Sanz, JF; Lambert, RM
Source: Journal of the American Chemical Society, 137 (2015) 940-947

abstract | fulltext

Scanning tunneling microscopy, temperature-programmed reaction, near-edge X-ray absorption fine structure spectroscopy, and density functional theory calculations were used to study the adsorption and reactions of phenylacetylene and chlorobenzene on Ag(100). In the absence of solvent molecules and additives, these molecules underwent homocoupling and Sonogashira cross-coupling in an unambiguously heterogeneous mode. Of particular interest is the use of silver, previously unexplored, and chlorobenzene—normally regarded as relatively inert in such reactions. Both molecules adopt an essentially flat-lying conformation for which the observed and calculated adsorption energies are in reasonable agreement. Their magnitudes indicate that in both cases adsorption is predominantly due to dispersion forces for which interaction nevertheless leads to chemical activation and reaction. Both adsorbates exhibited pronounced island formation, thought to limit chemical activity under the conditions used and posited to occur at island boundaries, as was indeed observed in the case of phenylacetylene. The implications of these findings for the development of practical catalytic systems are considered.

January, 2015 | DOI: 10.1021/ja5115584

Title: Theory and Practice: Bulk Synthesis of C3B and its H2- and Li-Storage Capacity
Author(s): King, TC; Matthews, PD; Glass, H; Cormack, JA; Holgado, JP; Leskes, M; Griffin, JM; Scherman, OA; Barker, PD; Grey, CP; Dutton, SE; Lambert, RM; Tustin, G; Alavi, A; Wright, DS
Source: Angewandte Chemie International Edition, 54 (2015) 5919-5923

abstract | fulltext

Previous theoretical studies of C3B have suggested that boron-doped graphite is a promising H2- and Li-storage material, with large maximum capacities. These characteristics could lead to exciting applications as a lightweight H2-storage material for automotive engines and as an anode in a new generation of batteries. However, for these applications to be realized a synthetic route to bulk C3B must be developed. Here we show the thermolysis of a single-source precursor (1,3-(BBr2)2C6H4) to produce graphitic C3B, thus allowing the characteristics of this elusive material to be tested for the first time. C3B was found to be compositionally uniform but turbostratically disordered. Contrary to theoretical expectations, the H2- and Li-storage capacities are lower than anticipated, results that can partially be explained by the disordered nature of the material. This work suggests that to model the properties of graphitic materials more realistically, the possibility of disorder must be considered.

May, 2015 | DOI: 10.1002/anie.201412200

Title: Fine Tuning the Emission Properties of Nanoemitters in Multilayered Structures by Deterministic Control of their Local Photonic Environment
Author(s): Alberto Jiménez-Solano, Juan Francisco Galisteo-López and Hernán Míguez
Source: Small, 11 (2015) 2727-2732

abstract | fulltext

Deterministic control on the dynamics of organic nanoemitters is achieved through precise control of its photonic environment. Resonators are fabricated by a combination of spin- and dip-coating techniques, which allows placement of the emitters at different positions within the sample, thus acting as a probe of the local density of states.

June, 2015 | DOI: 10.1002/smll.201402898

Title: Sunlight Absorption Engineering for Thermophotovoltaics: Contributions from the Optical Design
Author(s): Miguez, H
Source: ChemSusChem, 8 (2015) 786-788

abstract | fulltext

Nowadays, solar thermophotovoltaic systems constitute a platform in which sophisticated optical material designs are put into practice with the aim of achieving the long sought after dream of developing an efficient energy conversion device based on this concept. Recent advances demonstrate that higher efficiencies are at reach using photonic nanostructures amenable to mass production and scale-up.

March, 2015 | DOI: 10.1002/cssc.201403361

Title: Optical Description of Mesostructured Organic-Inorganic Halide Perovskite Solar Cells
Author(s): Anaya, M; Lozano, G; Calvo, ME; Zhang, W; Johnston, MB; Snaith, HJ; Miguez, H
Source: Journal of Physical Chemistry Letters, 6 (2015) 48-53

abstract | fulltext

Herein we describe both theoretically and experimentally the optical response of solution-processed organic–inorganic halide perovskite solar cells based on mesostructured scaffolds. We develop a rigorous theoretical model using a method based on the propagation of waves in layered media, which allows visualizing the way in which light is spatially distributed across the device and serves to quantify the fraction of light absorbed by each medium comprising the cell. The discrimination between productive and parasitic absorption yields an accurate determination of the internal quantum efficiency. State-of-the-art devices integrating mesoporous scaffolds infiltrated with perovskite are manufactured and characterized to support the calculations. This combined experimental and theoretical analysis provides a rational understanding of the optical behavior of perovskite cells and can be beneficial for the judicious design of devices with improved performance. Notably, our model justifies the presence of a solid perovskite capping layer in all of the highest efficiency perovskite solar cells based on thinner mesoporous scaffolds.

January, 2015 | DOI: 10.1021/jz502351s

Title: Environmental Effects on the Photophysics of Organic-Inorganic Halide Perovskites
Author(s): Galisteo-Lopez, JF; Anaya, M; Calvo, ME; Miguez, H
Source: Journal of Physical Chemistry Letters, 6 (2015) 2200-2205

abstract | fulltext

The photophysical properties of films of organic-inorganic lead halide perovskites under different ambient conditions are herein reported. We demonstrate that their luminescent properties are determined by the interplay between photoinduced activation and darkening processes, which strongly depend on the atmosphere surrounding the samples. We have isolated oxygen and moisture as the key elements in each process, activation and darkening, both of which involve the interaction with photogenerated carriers. These findings show that environmental factors play a key role in the performance of lead halide perovskites as efficient luminescent materials.

June, 2015 | DOI: 10.1021/acs.jpclett.5b00785

Title: Evolution of H-2 photoproduction with Cu content on CuOx-TiO2 composite catalysts prepared by a microemulsion method
Author(s): Kubacka, A; Munoz-Batista, MJ; Fernandez-Garcia, M; Obregon, S; Colon, G
Source: Applied Catalysis B: Environmental, 163 (2015) 214-222

abstract | fulltext

Copper oxides in contact with anatase correspond to promising materials with high activity in the photo-production of hydrogen by aqueous reforming of alcohols. By a single pot microemulsion method we obtained a series of Cu-Ti composite systems with controlled copper content in the 0-25 wt.% range. The scanning of such a wide range of composition led to the discovery of two well differentiated maxima in the photo-reaction performance. These maxima present rather high and relatively similar reaction rates and photonic efficiencies but are ascribed to the presence of different copper species. A multi-technique analysis of the materials indicates that the maxima obtained comes from optimizing different steps of the reaction; while the first would be connected with a positive effect on anatase charge handling performance the second seems exclusively related to electron capture by surface copper species.

February, 2015 | DOI: 10.1016/j.apcatb.2014.08.005

Title: Nanocolumnar 1-dimensional TiO2 photoanodes deposited by PVD-OAD for perovskite solar cell fabrication
Author(s): Javier Ramos, F.; Oliva-Ramirez, Manuel; Nazeeruddin, Mohammad Khaja; Graetzel, Michael; Gonzalez-Elipe, Agustin R.; Ahmad, Shahzada
Source: Journal of Materials Chemistry A, 3 (2015) 13291-13298

abstract | fulltext

Perovskite solar cells have attracted increasing interest among the photovoltaic community in the last few years owing to their unique properties and high efficiency. In the present work, we report the fabrication of perovskite solar cells based on highly ordered 1-dimensional porous TiO2 photoanodes, which are uniform on a large area. These nanocolumnar porous TiO2 photoanodes were deposited by physical vapor deposition in an oblique angle configuration (PVD-OAD) by varying the zenithal angle between the target and the substrate normal. Perovskite infiltration into these 1-dimensional nanocolumnar structures was homogeneous through the entire thickness of the porous layer as revealed by secondary ion mass spectroscopy studies. The fabricated solar cells, with an optimized thickness of the photoanode and with industrially accepted methods, will pave the way for easy implementation on a large scale.

July, 2015 | DOI: 10.1039/c5ta02238j

Title: Synthesis and application of layered titanates in the photocatalytic degradation of phenol
Author(s): Ivanova, S; Penkova, A; Hidalgo, MD; Navio, JA; Romero-Sarria, F; Centeno, MA; Odriozola, JA
Source: Applied Catalysis B: Environmental, 163 (2015) 23-29

abstract | fulltext

This study proposes a direct synthetic route to single titanate sheets through the mild and versatile conditions of the “chimie douce”. The stages of the production include the complexation of the titanium alkoxide precursor by benzoic acid, the formation of titanium oxo-clusters and their controlled transformation into single sheet titanates during the hydrolysis stage. The resulted material appears to be an excellent precursor for self-organized TiO2 nanotubes formation which presents an excellent activity as photocatalyst in the photo-degradation of phenol.

February, 2015 | DOI: 10.1016/j.apcatb.2014.07.048

Centro de Investigaciones Científicas Isla de la Cartuja. C/Américo Vespucio, 49 - 41092 Sevilla (España)
Tel.: [+34] 954489527 | Fax: [+34] 954460165 | buzon@icmse.csic.es