Joel Varley

Contact information:

Lawrence Livermore National Laboratory
7000 East Avenue, L-413
Livermore, CA 94550
email: varley2@llnl.gov
phone: 
fax: 925-422-6594

Education:

  • Ph.D. in Physics, University of California, Santa Barbara, 2011
  • B.S. in Physics, University of North Carolina, Chapel Hill, 2005

Research interests:

  • Tailoring electronic and optical properties of semiconductors and insulators via defect-engineering
  • CO2/CO reduction inspired by nature; enzyme catalysis

Some recent publications:

Oxide and electronics-related:

  • Descriptor-Based Approach for the Prediction of Cation Vacancy Formation Energies and Transition Levels. J. Phys. Chem. Lett. 5059–5063 (2017).
  • High-Throughput Design of Non-oxide p-Type Transparent Conducting Materials: Data Mining, Search Strategy, and Identification of Boron Phosphide. Chem. Mater. 29, 2568–2573 (2017).
  • Defects in AlN as candidates for solid-state qubits. Phys. Rev. B 93, 161201 (2016).
  • (InxGa1−x)2O3 alloys for transparent electronics. Phys. Rev. B 92, 085206 (2015).
  • Effect of chlorination on the TlBr band edges for improved room temperature radiation detectors. Phys. Status Solidi B 252, 1266–1271 (2015).
  • Electronic structure and defect properties of B6O from hybrid functional and many-body perturbation theory calculations: A possible ambipolar transparent conductor, J.B. Varley, V. Lordi, A. Miglio, G. Hautier Phys. Rev. B 90, 045205 (2014).
  • Hydrogenated vacancies and hidden hydrogen in SrTiO3, J.B. Varley, A. Janotti, C.G. Van de Walle, Phys. Rev. B 89, 075202 (2014).
  • Ambipolar doping in SnO, J.B. Varley, A. Schleife, A. Janotti, C.G. Van de Walle, Appl. Phys. Lett. 103, 082118 (2013).
  • Role of self-trapping in luminescence and p-type conductivity of wide-band-gap oxides, J.B. Varley, A. Janotti, C. Franchini, C.G. Van de Walle, Phys. Rev. B 85, 081109(R) (2012).
  • Hydrogenated cation vacancies in semiconducting oxides, J.B. Varley, H. Peelaers, A. Janotti, C.G. Van de Walle, J. Phys.: Condens. Matter 23, 334212 (2011).
  • Defects in SiC for quantum computing, J.R. Weber, W.F. Koehl, J.B. Varley, A. Janotti, B.B. Buckley, C.G. Van de Walle, D.D. Awschalom, J. Appl. Phys. 109, 102417 (2011); Vir. J. Nan. Sci. & Tech. 23, 23 (2011); Vir. J. Quantum Inf. 11, 6 (2011).
  • Tin dioxide from first principles: Quasiparticle electronic states and optical properties, A. Schleife, J.B. Varley, F. Fuchs, C. Rodl, F. Bechstedt, P. Rinke, A. Janotti, C.G. Van de Walle, Phys. Rev. B 83, 035116 (2011).
  • Hydrogen donors in SnO2 studied by infrared spectroscopy and first-principles calculations,W.M.H. Oo, S. Tabatabaei, M.D. McCluskey, J.B. Varley, A. Janotti, C.G. Van de Walle, Phys. Rev. B 82, 193201 (2010).
  • Oxygen vacancies and donor impurities in β-Ga2O3, J.B. Varley, J.R. Weber, A. Janotti, C.G. Van de Walle, Appl. Phys. Lett. 97, 142106 (2010).
  • Quantum computing with defects, J.R. Weber, W.F. Koehl, J.B. Varley, A. Janotti, B.B. Buckley, C.G. Van de Walle, D.D. Awschalom, Proc. Natl. Acad. Sci. 107, 19 (2010).
  • Hybrid functional studies of the oxygen vacancy in TiO2, A. Janotti, J.B. Varley, P. Rinke, N. Umezawa, G. Kresse, C.G. Van de Walle, Phys. Rev. B 81, 085212 (2010).

Battery-related:

  • Carbon incorporation and anion dynamics as synergistic drivers for ultrafast diffusion in superionic LiCB11H12 and NaCB11H12. Adv. Energy Mat. (in press, 2018).
  • Structural, Chemical, and Dynamical Frustration: Origins of Superionic Conductivity in closo-Borate Solid Electrolytes. Chem. Mater. 29, 9142–9153 (2017).
  • Understanding Ionic Conductivity Trends in Polyborane Solid Electrolytes from Ab Initio Molecular Dynamics. ACS Energy Lett. 2, 250–255 (2017).
  • Lithium and oxygen vacancies and their role in Li2O2 charge transport in Li-O2 batteries., Energy Environ. Sci. 7, 720 (2014).
  • Tunneling and Polaron Charge Transport through Li2O2 in Li–O2 Batteries. J. Phys. Chem. Lett. 4, 3494–3499 (2013).

Solar-related:

  • Exploring Cd-Zn-O-S alloys for improved buffer layers in thin-film photovoltaics. Phys. Rev. Materials 1, 025403 (2017).
  • Stability of Cd1-xZnxOyS1-y Quaternary Alloys Assessed with First-Principles Calculations. ACS Appl. Mater. Interfaces 9, 5673–5677 (2017).
  • A comparison of point defects in Cd1-xZnxTe1-ySey crystals grown by Bridgman and traveling heater methods. J. Appl. Phys. 121, 125705 (2017).
  • First principles calculations of point defect diffusion in CdS buffer layers: Implications for Cu(In,Ga)(Se,S)2 and Cu2ZnSn(Se,S)4-based thin-film photovoltaics. J. Appl. Phys. 119, 025703 (2016).
  • Intermixing at the absorber-buffer layer interface in thin-film solar cells: The electronic effects of point defects in Cu(In,Ga)(Se,S)2 and Cu2ZnSn(Se,S)4 devices. J. Appl. Phys. 116, 063505 (2014).
  • Electrical properties of point defects in CdS and ZnS, J.B. Varley, V. Lordi, Appl. Phys. Lett. 103, 102103 (2013).

Catalysis-related:

  • The Mechanism of CO and CO2 Hydrogenation to Methanol over Cu-Based Catalysts. ChemCatChem 7, 1105–1111 (2015).
  • Mechanistic insights into nitrogen fixation by nitrogenase enzymes. Phys. Chem. Chem. Phys. 17, 29541–29547 (2015).
  • Ni–Fe–S cubanes in CO2 reduction electrocatalysis: A DFT study, J.B. Varley, H.A. Hansen, N.L. Ammititzbøll, L.C. Grabow, A.A. Peterson, J.K. Nørskov, ACS Catal. 3, 2640 (2013). 
  • Understanding trends in the electrocatalytic activity of metals and enzymes for CO2 reduction to CO, H.A. Hansen, J.B. Varley, A.A. Peterson, J.K. Nørskov, Phys. Chem. Lett. 4, 388 (2013).
  • First-principles calculations of Fischer-Tropsch processes catalyzed by nitrogenase enzymes, J.B. Varley, J.K. Nørskov, ChemCatChem 5, 732 (2012).
  • Mechanism of visible-light photocatalysis in nitrogen-doped TiO2, J.B. Varley, A. Janotti, C.G. Van de Walle, Advanced Materials 23, 2343 (2011).