Person: Molina Ontoria, Agustín
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First Name
Agustín
Last Name
Molina Ontoria
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Orgánica
Area
Identifiers
7 results
Search Results
Now showing 1 - 7 of 7
Item Diarylamino-substituted Tetraarylethene (TAE) as Efficient and Robust Hole Transport Material for 11% Methyl Ammonium Lead Iodide Perovskite Solar Cells.(Chemical Communications, 2015) Cabau, Lydia; García Benito, Inés; Molina Ontoria, Agustín; Martín, Nazario; Montcada, Nuria F.; Vidal Ferran, Anton; Palomares, EmilioWe report the synthesis and characterisation of tetra{4-[N,N-(4,4′-dimethoxydiphenylamino)]phenyl}ethene (TAE-1) as an efficient and robust hole transport material for its application in methyl ammonium lead iodide (MAPI) perovskite solar cells. The solar cells show light-to-energy conversion efficiencies as high as 11.0% under standard measurement conditions without the need of additional dopants.Item Nanoelectrical analysis of single molecules and atomic-scale materials at the solid/liquid interface(Nature Materials, 2014) Nirmalraj, Peter; Thompson, Damien; Molina Ontoria, Agustín; Sousa, Marilyne; Martín, Nazario; Gotsmann, Bernd; Riel, HeikeEvaluating the built-in functionality of nanomaterials under practical conditions is central for their proposed integration as active components in next-generation electronics. Low-dimensional materials from single atoms to molecules have been consistently resolved and manipulated under ultrahigh vacuum at low temperatures. At room temperature, atomic-scale imaging has also been performed by probing materials at the solid/liquid interface. We exploit this electrical interface to develop a robust electronic decoupling platform that provides precise information on molecular energy levels recorded using in situ scanning tunnelling microscopy/spectroscopy with high spatial and energy resolution in a high-density liquid environment. Our experimental findings, supported by ab initio electronic structure calculations and atomic-scale molecular dynamics simulations, reveal direct mapping of single-molecule structure and resonance states at the solid/liquid interface.We further extend this approach to resolve the electronic structure of graphene monolayers at atomic length scales under standard room-temperature operating conditions.Item Analysis of the Hysteresis Behavior of Perovskite Solar Cells with Interfacial Fullerene Self-Assembled Monolayers(Journal of physical chemistry letters, 2016) Valles Pelarda, Marta; Clasen Hames, Bruno; García Benito, Inés; Almora, Osbel; Molina Ontoria, Agustín; Sánchez, Rafael S.; García Belmonte, Germà; Martín, Nazario; Mora Sero, IvánThe use of self-assembled monolayers (SAMs) of fullerene derivatives reduces the hysteresis of perovskite solar cells (PSCs). We have investigated three different fullerene derivatives observing a decrease on hysteresis for all the cases. Several processes can contribute to the hysteresis behavior on PSCs. We have determined that the reduced hysteresis observed for devices with SAMs is produced by a decrease of the capacitive hysteresis. In addition, with an appropriated functionalization, SAMs can increase photocurrent even when no electron selective contact (ESC) is present and a SAM is deposited just on top of the transparent conductive oxide. Appropriated functionalization of the fullerene derivative, as introducing −CN groups, can enhance cell performance and reduce hysteresis. This work paves the way for a future enhancement of PSCs by a tailored design of the fullerene molecules that could actuate as an ESC by themselves.Item Fingerprints of Through-Bond and Through-Space Exciton and Charge Conjugations in Linearly Extended [2,2]Paracyclophanes(Journal of the American Chemical Society, 2017) Zafra, José L.; Molina Ontoria, Agustín; Mayorga Burrezo, Paula; Peña Avarez, Miriam; Samoc, Marek; Szeremeta, Janusz; Ramínez, Francisco J.; Lovander, Matthew D.; Droske, Christopher J.; Pappenfus, Ted M.; Echegoyen, Luis; López Navarrete, Juan T.; Martín, Nazario; Casado, JuanNew stilbenoid and thiophenic compounds terminally functionalized with donor-donor, acceptor-acceptor and donoracceptor moieties and substituting a central [2,2]paracyclophane unit have been prepared and their properties interpreted in terms of through-bond and through space conjugations. A description of the excited state properties based on photophysical data and with focus on the participation of the central [2,2]paracyclophane, or “phane” state, in competition with through-bond conjugation in the arms has been conducted. To this end, one-photon absorption and emission spectroscopy, as a function of temperature, of solvent polarity in solution and of pressure in solid state have been carried out. Furthermore, the analysis of charge delocalization in the face-toface [2,2]paracyclophane part in the neutral state and in the oxidized species (dications and trications) has been assessed allowing to elucidate the vibrational Raman fingerprint of charge delocalization in these systems. Thus, a complementary approach to “intermolecular” excitation and charge delocalization has been presented in [2,2]paracyclophane model systems by means of the pertinent spectroscopic techniques.Item Benzotrithiophene-Based Hole-Transporting Materials for 18.2% Perovskite Solar Cells(Angewandte Chemie, 2016) Molina Ontoria, Agustín; Zimmermann, Iwan; García Benito, Inés; Gratia, Paul; Roldán Carmona, Cristina; Aghazada, Sadig; Graetzel, Michael; Khaja Nazeeruddin, Mohammad; Martín León, NazarioNew star-shaped benzotrithiophene (BTT)-based hole-transporting materials (HTM) BTT-1, BTT-2 and BTT-3 have been obtained through a facile synthetic route by crosslinking triarylamine-based donor groups with a benzotrithiophene (BTT) core. The BTT HTMs were tested on solution-processed lead trihalide perovskite-based solar cells.Power conversion efficiencies in the range of 16% to 18.2% were achieved under AM 1.5 sun with the three derivatives. These values are comparable to those obtained with todays most commonly used HTM spiro-OMeTAD, which point them out as promising candidates to be used as readily available and cost-effective alternatives in perovskite solar cells (PSCs).Item Determination of the Attenuation Factor () in Hybrid Covalent/Non-Covalent Molecular Wires(Angewandte chemie, 2016) Vela, Sonia; Bauroth, Stefan; Molina Ontoria, Agustín; Guldi, Dirk M.; Martín, NazarioWe have established for the first time the molecular wire behaviour in a new set of hybrid covalent/supramolecular porphyrinfullerene structures, in which hydrogen-bond interactions and pphenylene oligomers of different length act as highly efficient molecular wires exhibiting a remarkably low attenuation factor ( = 0.07 ± 0.01 Å1 ).Item Influence of alkyl chain length on the photovoltaic properties of dithienopyran-based hole-transporting materials for perovskite solar cells(Journal of Materials Chemistry C, 2023) Caicedo Reina, Mauricio; Pérez Escribano, Manuel; Urieta Mora, Javier; García Benito, Inés; Calbo, Joaquín; Ortiz, Alejandro; Insuasty, Braulio; Molina Ontoria, Agustín; Ortí, Enrique; Nazario Martín; Martín León, NazarioA tailored design of asymmetric hole-transporting materials (HTMs) is reported with the synthesis of a family of new HTMs based on the use of the 5H-dithieno[3,2-b:20 ,30 -d]pyran (DTP) moiety endowed with donor p-methoxytriphenylamines. A complete experimental and theoretical characterization of the optoelectronic, electrochemical and thermal properties is presented, showing more marked differences in the latter prompted by the different length of the alkyl chains (ethyl, butyl or hexyl) attached to the DTP core. This chemical design plays an important role in the morphological behavior of the new HTMs, displaying a different ability for the deposition on the top surface of the perovskite layer in perovskite solar cells (PSCs), as evidenced by scanning electron microscopy. The photovoltaic performance of the new DTP-based HTMs is highly affected by this morphological behavior, resulting in a maximum power conversion efficiency (PCE) of 17.39% for the ethyl derivative (DTPA-Et) in planar devices in combination with the state-of-the-art triple cation perovskite [(FAPbI3)0.87(MAPbBr3)0.13]0.92[CsPbI3]0.08. Otherwise, the hexyl derivative (DTPA-Hex) showed a decreased value of PCE of 15.04% due to its higher dispersity in chlorobenzene, resulting in a less uniform and lower quality film. In comparison, the reference cell using spiro-OMeTAD reaches a maximum PCE of 18.06%. This work demonstrates that DTP is a good candidate for the preparation of HTMs with high hole mobilities for exploitation in efficient and stable PSCs.