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A.L. Álvarez

Universidad Centroamericana José Simeón Cañas

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C. Coya

Universidad Rey Juan Carlos

Jesús Martín‐Gil

Universidad de Valladolid

A. de Andrés

Consejo Superior de Investigaciones Científicas

Pablo Martín‐Ramos

Universidad de Valladolid

Miguel García‐Vélez

Universidad Rey Juan Carlos

C. Zaldo

Instituto de Ciencia de Materiales de Madrid

Belén Arredondo

Universidad Rey Juan Carlos

Ricardo Mallavia

Universitat de Miguel Hernández d'Elx

F. Calle

Universidad Politécnica de Madrid

Manuela Ramos Silva

University of Coimbra

Cooperative Institutions

Universidad Politécnica de Madrid

Universidad Rey Juan Carlos

Consejo Superior de Investigaciones Científicas

Universidad Complutense de Madrid

Instituto de Ciencia de Materiales de Madrid

Universidad Autónoma de Madrid

Universitat de Miguel Hernández d'Elx

Universidad de Valladolid

European Telecommunications Standards Institute

University of Coimbra

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CCDC 997691: Experimental Crystal Structure Determination

The Cambridge Structural Database (2014)

Pablo Martín‐Ramos C. Coya V. Lavı́n I.R. Martı́n M. Ramos Silva

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Crystal (programming language)

10.5517/cc12h5lb

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New Concepts for Production of Scalable Single Layer Oxidized Regions by Local Anodic Oxidation of Graphene

Small (2019)

Sergio Quesada Fernando Borrás Miguel García‐Vélez C. Coya Esteban Climent‐Pascual

Abstract A deep comprehension of the local anodic oxidation process in 2D materials is achieved thanks to an extensive experimental and theoretical study of this phenomenon in graphene. This requires to arrange a novel instrumental device capable to generate separated regions of monolayer graphene oxide (GO) over graphene, with any desired size, from micrometers to unprecedented mm 2 , in minutes, a milestone in GO monolayer production. GO regions are manufactured by overlapping lots of individual oxide spots of thousands µm 2 area. The high reproducibility and circular size of the spots allows not only an exhaustive experimental characterization inside, but also establishing an original model for oxide expansion which, from classical first principles, overcomes the traditional paradigm of the water bridge, and is applicable to any 2D‐material. This tool predicts the oxidation behavior with voltage and exposure time, as well as the expected electrical current along the process. The hitherto unreported transient current is measured during oxidation, gaining insight on its components, electrochemical and transport. Just combining electrical measurements and optical imaging estimating carrier mobility and degree of oxidation is possible. X‐ray photoelectron spectroscopy reveals a graphene oxidation about 30%, somewhat lower to that obtained by Hummers' method.

10.1002/smll.201902817

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Relaxation of InGaAs layers grown on (111)B GaAs

Applied Physics Letters (1994)

A. Sacedón F. Calle A.L. Álvarez E. Calleja E. Muñoz

The relaxation behavior of InGaAs layers grown by molecular beam epitaxy on (111)B GaAs is investigated and compared with simultaneously grown (100) reference samples. Surface morphology, defect microstructure, and optical quality of the layers during the relaxation process are studied by Nomarski interference contrast, transmission electron microscopy, low-temperature photoluminescence, and Raman spectroscopy. These techniques reveal an inhomogeneous and anisotropic relaxation in (111) samples. In (111) samples, the increase of critical thickness and the slower relaxation dependence on thickness, as compared with the (100) reference samples, is discussed

10.1063/1.112415

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Citations (33)

Huge Photostability Enhancement in Bismuth-Doped Methylammonium Lead Iodide Hybrid Perovskites by Light-Induced Transformation

Chemistry of Materials (2019)

J. Bartolomé Esteban Climent‐Pascual Carlos Redondo-Obispo C. Zaldo A.L. Álvarez

The doping strategy of hybrid perovskites is being extensively explored not only for higher efficiency but also to overcome issues in photovoltaic materials such as self-degradation pathways in an ambient atmosphere or under visible irradiation. Here, BiI3 is introduced in the synthesis of MAPbI3 films (MA: CH3–NH3+) to stabilize the material. Around 25% of nominal Bi3+ is accommodated in the perovskite structure, producing a shrinking of the unit cell and a small increase of the band gap. The presence of empty Bi gap states quenches the 770 nm red interband emission and results in a near-infrared emission at 1100 nm. However, high enough visible irradiation density induces a progressive segregation of Bi3+ out of the perovskite lattice and promotes the re-emergence of the red emission. This emission is blue-shifted, and its intensity increases strongly with time until it reaches a saturation value which remains stable in the transformed films for extremely high power densities, around 1000 times higher than for undoped samples. We propose that the underlying processes include the formation of BiI3 and BiOI, probably at the surface of the crystals, hampering the usual decomposition pathways into PbI2 and PbOx for undoped MAPbI3. These results provide a new path for obtaining highly stable materials which would allow an additional boost of hybrid perovskite-based optoelectronics.

Bismuth

10.1021/acs.chemmater.9b00270

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Influence of the surface morphology on the relaxation of low-strained InxGa1 − xAs linear buffer structures

Journal of Crystal Growth (1997)

J.F. Valtueña A. Sacedón A.L. Álvarez I. Izpura F. Calle

Stress relaxation

Morphology

10.1016/s0022-0248(97)00377-1

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A Distributed Consensus Protocol with a Coordinator

F. Santana Sergio Arévalo A.L. Álvarez Francisco Javier Miranda González

Source

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Interplay between Interface Dislocations and Surface Kinetic: A Contribution to the Roughness of Strained Epitaxial Layers

Defect and diffusion forum/Diffusion and defect data, solid state data. Part A, Defect and diffusion forum (1998)

A.L. Álvarez F. Calle

Interface (matter)

10.4028/www.scientific.net/ddf.157-159.211

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Citations (1)

Active layer solution-processed NIR-OLEDs based on ternary erbium(iii) complexes with 1,1,1-trifluoro-2,4-pentanedione and different N,N-donors

Dalton Transactions (2014)

Pablo Martín‐Ramos C. Coya V. Lavı́n I.R. Martı́n Manuela Ramos Silva

Using a fluorinated 1,1,1-trifluoro-2,4-pentanedione (Htfac) ligand and either 2,2'-bipyridine (bipy), bathophenanthroline (bath) or 5-nitro-1,10-phenanthroline (5NO2phen) as an ancillary ligand, three new ternary erbium(iii) octacoordinated complexes have been synthesized. The single crystal structures of the new complexes (namely [Er(tfac)3(bipy)], [Er(tfac)3(bath)] and [Er(tfac)3(5NO2phen)]) have been determined and their properties have been investigated by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and thermodynamic analysis. After ligand-mediated excitation of these complexes in the UV, they all show the characteristic near-infrared (NIR) luminescence of the corresponding Er(3+) ion at 1532 nm. The same emission in the C-band transmission window can also be obtained from the solution-processed organic light-emitting diodes (OLEDs) with structure: glass/ITO/PEDOT:PSS/[Er(tfac)3(N,N-donor)]/Ca/Al. In spite of the fact that the photoluminescence intensity of [Er(tfac)3(5NO2phen)] is stronger than those of [Er(tfac)3(bipy)] and [Er(tfac)3(bath)], the best electroluminescence results correspond to the OLED based on the [Er(tfac)3(bath)] complex, as a consequence of the superior electron transport capabilities of bathophenanthroline.

10.1039/c4dt01694g

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Citations (30)

Star-shaped hexaaryltriindoles small molecules: Tuning molecular properties towards solution processed organic light emitting devices

Organic Electronics (2012)

C. Coya Constanza Ruiz A.L. Álvarez S. Álvarez‐García Eva M. García‐Frutos

Electron Mobility

Acceptor

Organic Electronics

Electron acceptor

10.1016/j.orgel.2012.06.018

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Citations (19)

NIR-OLED (1.54 μm) emitting electroluminescent diode arrays based on Er-complexes manufactured by cost-effective methods Matriz de diodos electroluminiscentes orgánicos emisores en el infrarrojo cercano (1.54 μm) basados en complejos de erbio fabricados por métodos de bajo coste

C. Coya A.L. Álvarez Miguel García‐Vélez Pablo Martín‐Ramos Manuela Ramos Silva

Solution processed 1.54 μm near infrared organic light-emitting diodes (NIR-OLED) based on novel Er(III) complexes, having the general formula [Er( -diketonate)3(N,Ndonor)], have been manufactured by cost-effective methods and their properties studied. 4,4,4-trifluoro-1-(2-naphthyl)1,3-butanedione (Htfnb or Hnta) or 1,1,1-trifuoro-5,5-dimethyl-2,4-hexanedione (Htpm) are the fluorinated -diketonate primary sensitizers, and 2,2’-bipyridine (bipy) or 5-nitro-1,10phenanthroline (5NO2phen) act as N,N-donors. The simple structure of the diodes is glass/indium-tin oxide (ITO)/poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)/[Er-complex]/Ca/Al. The resulting electroluminescence corresponds with the 4 I13/2→ 4 I15/2 Er(III) emission at 1.54 μm and no visible emission is observed. Photophysical characterization proves that, upon organic ligand excitation by UV light, the luminescence from the ligands is totally quenched in favour of 4I13/2→4I15/2 Er(III) emission, confirming a complete resonant energy transfer from the ligands to the Er(III) ion, analogous to that observed in the electroluminescence emission. We present a fabrication method that avoids any photolithographic or mask step. The reported results show a simple way to obtain large area NIR-OLEDs by cost-effective methods.

Indium tin oxide

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