Professional Education

  • Carl Zeiss Postdoctoral Fellow, TU Kaiserslautern, Physics (2018)
  • Postdoc, University of Arizona, Materials Science and Engineering (2016)
  • Doctor of Philosophy, University of Arizona, Physical Chemistry (2015)
  • Bachelors of Science, Beloit College, Chemistry and Art History (2009)

Stanford Advisors

All Publications

  • Hybridization-Induced Carrier Localization at the C-60/ZnO Interface ADVANCED MATERIALS Kelly, L. L., Racke, D. A., Kim, H., Ndione, P., Sigdel, A. K., Berry, J. J., Graham, S., Nordlund, D., Monti, O. A. 2016; 28 (20): 3960-+


    Electronic coupling and ground-state charge transfer at the C60 /ZnO hybrid interface is shown to localize carriers in the C60 phase. This effect, revealed by resonant X-ray photoemission, arises from interfacial hybridization between C60 and ZnO. Such localization at carrier-selective electrodes and interlayers may lead to severely reduced carrier harvesting efficiencies and increased recombination rates in organic electronic devices.

    View details for DOI 10.1002/adma.201503694

    View details for Web of Science ID 000376481400011

    View details for PubMedID 26596518

  • Spectroscopy and control of near-surface defects in conductive thin film ZnO JOURNAL OF PHYSICS-CONDENSED MATTER Kelly, L. L., Racke, D. A., Schulz, P., Li, H., Winget, P., Kim, H., Ndione, P., Sigdel, A. K., Bredas, J., Berry, J. J., Graham, S., Monti, O. A. 2016; 28 (9): 094007


    The electronic structure of inorganic semiconductor interfaces functionalized with extended π-conjugated organic molecules can be strongly influenced by localized gap states or point defects, often present at low concentrations and hard to identify spectroscopically. At the same time, in transparent conductive oxides such as ZnO, the presence of these gap states conveys the desirable high conductivity necessary for function as electron-selective interlayer or electron collection electrode in organic optoelectronic devices. Here, we report on the direct spectroscopic detection of a donor state within the band gap of highly conductive zinc oxide by two-photon photoemission spectroscopy. We show that adsorption of the prototypical organic acceptor C60 quenches this state by ground-state charge transfer, with immediate consequences on the interfacial energy level alignment. Comparison with computational results suggests the identity of the gap state as a near-surface-confined oxygen vacancy.

    View details for DOI 10.1088/0953-8984/28/9/094007

    View details for Web of Science ID 000370277700008

    View details for PubMedID 26871256

  • Disrupted Attosecond Charge Carrier De localization at a Hybrid Organic/Inorganic Semiconductor Interface JOURNAL OF PHYSICAL CHEMISTRY LETTERS Racke, D. A., Kelly, L. L., Kim, H., Schulz, P., Sigdel, A., Berry, J. J., Graham, S., Nordlund, D., Monti, O. A. 2015; 6 (10): 1935–41


    Despite significant interest in hybrid organic/inorganic semiconductor interfaces, little is known regarding the fate of charge carriers at metal oxide interfaces, particularly on ultrafast time scales. Using core-hole clock spectroscopy, we investigate the ultrafast charge carrier dynamics of conductive ZnO films at a hybrid interface with an organic semiconductor. The adsorption of C60 on the ZnO surface strongly suppresses the ultrafast carrier delocalization and increases the charge carrier residence time from 400 attoseconds to nearly 30 fs. Here, we show that a new hybridized interfacial density of states with substantial molecular character is formed, fundamentally altering the observed carrier dynamics. The remarkable change in the dynamics sheds light on the fate of carriers at hybrid organic/inorganic semiconductor interfaces relevant to organic optoelectronics and provides for the first time an atomistic picture of the electronically perturbed near-interface region of a metal oxide.

    View details for DOI 10.1021/acs.jpclett.5b00787

    View details for Web of Science ID 000355158600025

    View details for PubMedID 26263273

  • Tailoring Electron-Transfer Barriers for Zinc Oxide/C-60 Fullerene Interfaces ADVANCED FUNCTIONAL MATERIALS Schulz, P., Kelly, L. L., Winget, P., Li, H., Kim, H., Ndione, P. F., Sigdel, A. K., Berry, J. J., Graham, S., Bredas, J., Kahn, A., Monti, O. A. 2014; 24 (46): 7381–89
  • Unified photoemission spectroscopic picture of defect-driven charge carrier physics at an organic semiconductor/metal oxide interface Racke, D. A., Kelly, L. L., Schulz, P., Winget, P., Li, H., Kim, H., Sigdel, A., Berry, J. J., Graham, S., Bredas, J., Nordlund, D., Kahn, A., Monti, O. A. AMER CHEMICAL SOC. 2014
  • Electronic structure and dynamics of quasi-2D states of vanadyl naphthalocyanine on Au(111) MOLECULAR PHYSICS Ilyas, N., Kelly, L. L., Monti, O. A. 2013; 111 (14-15): 2175–88
  • Interfacial Electronic Structure of the Dipolar Vanadyl Naphthalocyanine on Au(111): "Push-Back" vs Dipolar Effects JOURNAL OF PHYSICAL CHEMISTRY C Terentjevs, A., Steele, M. P., Blumenfeld, M. L., Ilyas, N., Kelly, L. L., Fabiano, E., Monti, O. A., Della Sala, F. 2011; 115 (43): 21128–38

    View details for DOI 10.1021/jp204720a

    View details for Web of Science ID 000296172800041

  • Resonance and localization effects at a dipolar organic semiconductor interface JOURNAL OF CHEMICAL PHYSICS Steele, M. P., Kelly, L. L., Ilyas, N., Monti, O. A. 2011; 135 (12): 124702


    The image state manifold of the dipolar organic semiconductor vanadyl naphthalocyanine (VONc) on highly oriented pyrolytic graphite is investigated by angle-resolved two-photon photoemission (AR-TPPE) spectroscopy in the 0-1 monolayer regimes. Interfacial charge-transfer from the image potential state of clean graphite populates a near-resonant VONc anion level, identifiable by the graphite image potential state by its distinct momentum dispersion obtained from AR-TPPE. This affinity level is subject to depolarization by the neighboring molecules, resulting in stabilization of this state with coverage. Near a coverage of one monolayer, a hybrid image potential/anion state is also formed, showing progressive localization with coverage. Intensities for all these features develop rather differently with molecular coverage, pointing towards the different types of charge-transfer interactions at play at this interface.

    View details for DOI 10.1063/1.3637051

    View details for Web of Science ID 000295619700044

    View details for PubMedID 21974547

  • Ground and excited state interfacial electronic structure of a dipolar organic semiconductor on Au (111): Insights for interfacial electron transfer Monti, O. A., Steele, M. P., Ilyas, N., Kelly, L. L. AMER CHEMICAL SOC. 2011
  • Size controlled growth of sexithiophene islands on silicon oxide: Toward spatially resolved interfacial charge transfer studies in organic solar cells Kelly, L. L., Monti, O. A. AMER CHEMICAL SOC. 2009