Author Archive


Energy Alignment and Recombination in Perovskite Solar Cells: Weighted Influence on the Open Circuit Voltage
I. Gelmettia, N.F. Montcada, A. Pérez-Rodríguez, E. Barrena, C. Ocal, I. García-Benito, A. Molina-Ontoria, N. Martín, A. Vidal-Ferrana, E. Palomares
Energy and Environment Science 12 (2019) 1309-1316 DOI: 10.1039/C9EE00528E

Bipolar resistive switching on TiO2/Au by conducting Atomic Force Microscopy
M. Linares Moreau, M. Barella, L. López-Mir, N. Ghenzi, F. Golmar, L.P. Granja, C. Ocal, P. Levy
Materials Today: Proceedings 14 (2019) 100–103 DOI:10.1016/j.matpr.2019.05.062

Water adsorption, dissociation and oxidation on SrTiO3 and ferroelectric surfaces revealed by ambient pressure X-ray photoelectron spectroscopy
N. Domingo, E. Pach, K. Cordero-Edwards, V. Perez-Dieste, C. Escudero, A. Verdaguer
Phys. Chem. Chem. Phys. (2019) 21, 4920-4930 DOI: 10.1039/c8cp07632d

Effect of the Molecular Polarizability of SAMs on the Work Function Modification of Gold: Closed- versus Open-Shell Donor–Acceptor SAMs
V. Diez-Cabanes, D. C. Morales, M. Souto, M. Paradinas, F. Delchiaro, A. Painelli, C. Ocal, D. Cornil, J. Cornil, J. Veciana, I. Ratera
Adv. Mater. Technol. 4 (2019) 1800152   DOI: 10.1002/admt.201800152

Face dependent footprints of carpet-like graphene films grown on polycrystalline silicon carbide.
C. Ramírez, E. García,E. Barrena, A. De Pablos, M. Belmonte, M.I. Osendi, P. Miranzo, C. Ocal
Carbon 153 (2019) 417-427 

Pores Dominate Ice Nucleation on Feldspars
E. Pach, A. Verdaguer
J. Phys. Chem. C 123 (2019) 34, 20998–21004 DOI: 10.1021/acs.jpcc.9b05845

Surface charged species and electrochemistry of ferroelectric thin film
N. Domingo, I. Gaponenko, K. Cordero-Edwards, N. Stucki, V. Pérez-Dieste, C. Escudero, E. Pach, A. Verdaguer, P. Paruch
Nanoscale 11 (2019) 17920  DOI: 10.1039/c9nr05526f


Study of ice nucleation on surfaces focusing on the effect of surfaces on heterogeneous nucleation and ice growth at ambient conditions. (AV)

Ice is central to climate, geology and life. Understanding its behavior is essential for predicting the future of our planet. On average, 7% of the ocean’s surface is frozen; this alters ocean currents and limits the exchange of gases with seawater. Ice and snow coat 10% of the land permanently and up to half of the Northern Hemisphere in midwinter. Ice in clouds concentrate airborne chemicals and are sites were atmospheric chemistry takes place. Above the poles, clouds of ice grains host ozone-depleting reactions, forming holes in the stratospheric ozone layer at high latitudes that expose millions of people to increased ultraviolet radiation. Chemical reactions in snow on the ground can produce ozone and other environmental pollutants.  Yet the molecular mechanisms underlying these processes remain largely unknown.

Without knowing more about ice formation, it is impossible to build snow or ice-cloud modules for atmospheric and climate models or to extrapolate laboratory studies to environmental conditions with enough confidence. A few years ago it was established the ten questions that science needs to study to gain this knowledge. The first question raised was to understand how ice nucleation occurs on solid surfaces. Ice often forms easily on solid surfaces through heterogeneous nucleation. This happens at higher temperatures than homogeneous nucleation (i.e. with pure water only) and it’s directly responsible of most of the rain. To understand why that happens, the molecular bases of the interaction of water molecules with such surfaces need to be studied. The goal of this research line is to study ice nucleation induced by surfaces to be able to obtain the knowledge needed for the modification of natural surfaces or the design of artificial surfaces with controlled ice nucleation properties.


Selected recent publications:

 “Water at surfaces and interfaces: From molecules to ice and bulk liquid”
Shimizu,; Maier, S; Verdaguer, A; Velasco-Velez, JJ; Salmeron, M
Progress Surf. Sci. 93, 87-107, 2018. DOI: 10.1016/j.progsurf.2018.09.004

“Substrate Dependence of the Freezing Dynamics of Supercooled Water Films: A High-Speed Optical Microscope Study”
Pach, E; Rodriguez, L; Verdaguer, A. Phys. Chem. B 122, 818-826, 2018. DOI: 10.1021/acs.jpcb.7b06933

“Revealing Water Films Structure from Force Reconstruction in Dynamic AFM”
Calo, A; Domingo, N; Santos, S; Verdaguer, A. Phys. Chem. C, 119, 8258-8265, 2015. DOI: 10.1021/acs.jpcc.5b02411

“Communication: Growing room temperature ice with graphene”
Verdaguer, A; Segura, JJ; Lopez-Mir, L; Sauthier, G; Fraxedas, J. Chem Phys., 138, 121101, 2013. DOI: 10.1063/1.4798941

Study of the interaction of water with ferroelectric surfaces and its role in surface charge screening using SPM and AP-XPS techniques. (AV)

Ferroelectric materials are polar materials with a permanent electric dipole below a certain transition temperature. This polarization can be controlled and switched by externally applied electric fields, for example to build thin-film ferroelectric memories. At the surface of ferroelectric materials, polarization suffers from serious fundamental and practical challenges such as depolarization fields and surface charge screening. Uncompensated surface charges due to the discontinuity of the normal polarization component result in depolarization fields that strongly affect polarization states. The ultimate stability of ferroelectric phases is determined by a balance between bulk thermodynamics and the screening mechanisms for polarization, which can be internal (domain formation or charge carriers migration within the bulk) or external (chemical environment or adsorbates). Understanding the interplay between ferroelectric phase stability, screening, and atomistic processes at the surface is key to control low-dimensional ferroelectricity. The interplay between polarization and surface adsorbates works in both directions: adsorbates influence polarization, but the orientation of the polarization also determines the type of adsorbates that bond at the surfaces, and it has been demonstrated that ferroelectric surfaces with opposite polarity can have different behavior toward molecules adsorption.

In this research line we focus our interest in studying surface screening mechanisms on ferroelectric materials using Piezoresponse Force Microscopy (PFM) and Ambient Pressure Photoelectron Spectroscopy (AP-XPS). AP-XPS allow us to obtain direct information of the different chemical species that form at the ferrolectric surface in contact with water vapor and other gases present in the ambient were devices containing ferrolectric materials are expected to work. 


Selected recent publications:

 “Water adsorption, dissociation and oxidation on SrTiO3 and ferroelectric surfaces revealed by ambient pressure X-ray photoelectron spectroscopy”
Domingo, N; Pach, E; Cordero-Edwards, K; Perez-Dieste, V; Escudero, C; Verdaguer, A. 
Phys. Chem. Chem. Phys.  21, 4920-4930, 2019. DOI: 10.1039/c8cp07632d

“Water Affinity and Surface Charging at the z-Cut and y-Cut LiNbO3 Surfaces: An Ambient Pressure X-ray Photoelectron Spectroscopy Study”
Cordero-Edwards, K; Rodriguez, L; Calo, A; Esplandiu, MJ; Perez-Dieste, V; Escudero, C; Domingo, N; Verdaguer, A
Phys. Chem. C 120, 24048-24055, 2016 DOI: 10.1021/acs.jpcc.6b05465

“Surface screening of written ferroelectric domains in ambient conditions” 
Segura, JJ; Domingo, N; Fraxedas, J; Verdaguer, A. 
Appl. Phys. 113, 187213, 2013. DOI: 10.1063/1.4801983


Development of new SPM modes based in multifrequency dynamic Atomic Force Microscopy (AFM) to study wetting, ice nucleation and identification of chemical groups at the nanoscale. (AV)

Water/solid interfaces are of fundamental interest in various fields including geology, metrology, biology, and chemistry. Despite its simple molecular structure the structure and interactions of water with surfaces, which determines wetting and reactivity remain unsolved. The knowledge of this structure at the nanoscale is crucial to understand key properties that determine corrosion, dissolution, and electrochemical processes. In this research line we use Scanning Probe  (SPM) techniques to study water/solid interfaces at the nanoscale. One of the differences of SPM from other techniques is the locality of the information. SPM uses a probe tip to scan over the surface, and obtain structural information together with, e.g., electronic, mechanical, and vibrational properties. Because it is not an averaged information over a wide area, as in the case of all the other techniques listed above, detailed investigations of how atomic steps, kinks, and defects residing on the surface influence on the adsorption of molecules are possible.  However using SPM to study water/solid interfaces is not a straightforward technique because of the perturbations that the SPM probe can cause on the water films during measurements. Non-contact SPM techniques to avoid direct interaction between the SPM probe and water have been developed in the group. Those techniques are being used now to go a step forward and try to create new SPM modes that could allow to identify at the nanoscale between different organic chemical groups.


Selected recent publications:

 “Water at surfaces and interfaces: From molecules to ice and bulk liquid”
Shimizu,; Maier, S; Verdaguer, A; Velasco-Velez, JJ; Salmeron, M.
Progress Surf. Sci. 93, 87-107, 2018. DOI: 10.1016/j.progsurf.2018.09.004

“Imaging Water Thin Films in Ambient Conditions Using Atomic Force Microscopy”
Santos, S; Verdaguer, A.
Materials 9, 182, 2016. DOI: 10.3390/ma9030182

“A nanoscopic approach to studying evolution in graphene wettability”
Lai, CY; Tang, TC; Amadei, CA; Marsden, AJ; Verdaguer, A; Wilson, N; Chiesa, M. 
Carbon 80, 784-792, 2016. DOI: 10.1016/j.carbon.2014.09.034

“Minimal Invasiveness and Spectroscopy-Like Footprints for the Characterization of Heterogeneous Nanoscale Wetting in Ambient Conditions”
Amadei, CA; Santos, S; Pehkonen, SO; Verdaguer, A; Chiesa, M.
Phys. Chem. C, 117, 20819-20825, 2013 DOI: 10.1021/jp408984h

“Measuring the true height of water films on surfaces” 
Santos, S; Verdaguer, A; Souier,  ; Thomson, NH ; Chiesa, M. 
Nanotechnology  22, 465705, 2011 DOI: 10.1088/0957-4484/22/46/465705


Real Space Demonstration of Induced Crystalline 3D Nanostructuration of Organic Layers
Markos Paradinas, Ana Pérez-Rodríguez, Esther Barrena, Carmen Ocal
J. Phys. Chem. B (2018) 122(2), 633−639DOI: 10.1021/acs.jpcb.7b05342

In-situ Scrutiny of the Relationship between Polymorphic Phases and Properties of Self-Assembled Monolayers of a Biphenyl Based Thiol 
Markos Paradinas, Carmen Munuera, Manfred Buck, Carmen Ocal
J. Phys. Chem. B (2018) 122(2), 657-665DOI: 10.1021/acs.jpcb.7b05958

Decoding the vertical phase separation and its impact on C8-BTBT:PS transistor properties
Ana Pérez-Rodríguez, Inés Tremiño, Carmen Ocal, Marta Mas-Torrent, Esther Barrena
ACS Appl. Mater. Interfaces (2018) 10 (8), 7296–7303DOI: 10.1021/acsami.7b19279

Electron Accumulative Molecules
B. Buades, V. Sanchez Arderiu, D. Olid-Britos, Cl. Viñas, R. Sillanpää, M. Haukka, X. Fontrodona, M. Paradinas, C. Ocal, F. Teixidor 
J. Am. Chem. Soc. (2018), 140(8), 2957-2970 DOI: 10.1021/jacs.7b12815

Solving the long-standing controversy of long-chain alkanethiols surface structure on Au(111)
X. Torrelles, E. Pensa, E. Cortés, R. Salvarezza, P. Carro, C. Hernández Guerrero, C. Ocal, E. Barrena, S. Ferrer
J. Phys. Chem, C (2018), 122 (7), 3893–3902 DOI: 

Boosting Self-Assembly Diversity in the Solid-State by Chiral/non-Chiral ZnII-Porphyrin Crystallization
Wenjie Qian, Arántzazu González-Campo, Ana Pérez-Rodríguez, Sabina Rodríguez-Hermida, Inhaz Imaz, Klaus Wurst, Daniel Maspoch, Eliseo Ruiz, Carmen Ocal, Esther Barrena, David B. Amabilino, and Núria Aliaga-Alcalde
Chem. Eur. J. (2018) 24,12950 –12960 DOI: 10.1002/chem.201802031

Chiral organization and Charge Redistribution in Chloroaluminum Phtalocyanine on Au(111) Beyond the Monolayer
S. Matencio, R. Palacios-Rivera, J.I. Martínez, C. Ocal and E. Barrena
J. Phys. Chem, C (2018) 122 (28), 16033–16041 DOI: 10.1021/acs.jpcc.8b02385

Enantiopure Supramolecular Motifs of Self-assembled Diamine-based Chiral Molecules on Cu(100)
R. Palacios-Rivera, E. Barrena,  J. Faraudo, P. Gargiani, M.A. Niño, D. Arvanitis, I. Kowalik, J.J. de Miguel and Carmen Ocal
J. Phys. Chem, C (2018)122 (42), 24129–24136 DOI: 10.1021/acs.jpcc.8b07322

Water at surfaces and interfaces: From molecules to ice and bulk liquid
Tomoko K. Shimizu, Sabine Maier, Albert Verdaguer, Juan-Jesus Velasco-Velez, Miquel Salmeron
Progress in Surface Science DOI: 10.1016/j.progsurf.2018.09.004

Substrate Dependence of Freezing Dynamics of Supercooled Water Films: A High-Speed Optical Microscope Study
E. Pach, L. Rodriguez, and A. Verdaguer
J. Phys. Chem. B, 2018, 122, 818-826 DOI: 10.1021/acs.jpcb.7b06933

A Model for the Characterization of the Polarizability of Thin Films Independently of the Thickness of the Film
M. Sacha, A. Verdaguer, M. Salmeron
J. Phys. Chem. B, 2018, 122, 904-909 DOI: 10.1021/acs.jpcb.7b06975




Microfluidic Pneumatic Cages: A Novel Approach for In-chip Crystal Trapping, Manipulation and Controlled Chemical Treatment

Abrishamkar, A., Paradinas, M., Bailo, E., Rodriguez-Trujillo, R., Pfattner, R., Rossi, R. M., et al. Microfluidic Pneumatic Cages: A Novel Approach for In-chip Crystal Trapping, Manipulation and Controlled Chemical Treatment. J. Vis. Exp. (113), e54193, doi:10.3791/54193 (2016). Date Published: 7/12/2016, Issue 113doi: 10.3791/54193

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