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Ben Schwartz
                          photo Benjamin J.
                          Schwartz
Department of Chemistry and Biochemistry, UCLA

Professor

B.S. in Physics and Chemistry, University of Michigan; Ph.D., University of California at Berkeley (Advisor:  Charles B. Harris); NSF Postdoctoral Fellow in Chemistry, University of Texas at Austin (Advisor:  Peter J. Rossky); Postdoctoral Fellow, University of California at Santa Barbara (Advisor:  Alan J. Heeger).   Senior Editor, the Journal of Physical Chemistry; UCLA Distinguished Teaching Award; Herbert Newby McCoy Award for Outstanding Research; Hanson-Dow Award for Excellence in Teaching; Camille Dreyfus Teacher-Scholar; Glenn T. Seaborg Award; Alfred P. Sloan Foundation Research Fellow; Research Corporation Cottrell Scholar Award; NSF CAREER Award in Chemistry; NSF Predoctoral Fellow; W. R. Grace and Co. Predoctoral Fellow.

Brief CV 

 
Research

Our research is directed at building a molecular-level understanding of chemical reactivity in complex environments by studying the dynamics of condensed phase chemical reactions using both experimental and theoretical techniques: femtosecond lasers and molecular dynamics computer simulations. Our research efforts fall into two principle areas: studies of how solvent molecules control the choice of products or the rate of solution-phase chemical reactions, and investigations into the ultrafast photophysics and electronic structure of semiconducting polymer-based solar cells.  We also have worked in the past at fabricating three-dimensional microstructures using multiphoton lithography.

Our first main area of research centers around solvent effects on chemical reactivity. As a chemical reaction takes place in solution, chemical bonds are broken and formed and electrical charge is redistributed between reactants and products. The solvent environment responds (via molecular reorientation or translation) to these changes in charge distribution and in size and shape of the reacting species on a variety of time scales extending from femtoseconds to longer than microseconds. In our group, we use femtosecond pump-probe spectroscopies to experimentally monitor the course of solution phase chemical reactions in real time. With femtosecond time resolution, we are able to "watch" the motions of solvent molecules responding to chemical changes of reacting solutes, monitor the flow of energy between reacting species and the solvent, and identify the motion of electrons during charge transfer reactions. These experiments are accompanied by computer simulations, ranging from simple solutions of Newton's classical equations of motion to sophisticated algorithms allowing for quantum dynamics in the absence of the Born-Oppenheimer approximation. Our group develops new techniques for deriving the pseudopotentials needed in mixed quantum/classical simulations, solving the Schr´┐Żdinger equation for electrons that reside largely between molecules, and calculating the free energies of quantum-mechanical objects in condensed phases.  Our simulations provide molecular detail that is unavailable from experiment; on the computer, for example, we can easily separate the roles of solvent rotational and translational motions in solvating a chemical species or in providing the energy needed to promote a charge transfer reaction.  Projects range from studies of model systems such as solvated electrons to investigations of large organic molecules with complex photochemistry.  Simulations are done in close connection to the femtosecond experiments, so that experimental results drive new simulations and vice-versa, providing students in the group with an opportunity to do both experimental and theoretical work. 

Our second main area of research is focused on the electronic structure of conjugated polymers. Conjugated polymers are remarkable materials that have the electrical properties of semiconductors but the mechanical properties and processing advantages of plastics. This gives these materials enormous commercial potential for use in light-emitting diodes, displays and photodetectors that have large areas and are flexible. Upon photoexcitation, the electrons and holes created in semiconducting polymers interact with their environment, leading to relaxation processes on multiple time scales; many of the important dynamical issues are qualitatively similar to the solution-phase reactions discussed above. For polymer-based photovoltaics, the polymers are blended with an electron acceptor, usually a fullerene derivative, and the nanometer-scale morphology of the blend is critical to device performance.  Thus, much of our work focuses on understanding the relationship between the structure and function of polymer-based solar cells so that the morphology can be controlled and optimized for different applications.  We work to achieve this goal using information from femtosecond and steady-state spectroscopies, scanning probe microscopies, simulations and the device physics of  working polymer solar cells. Projects include: spectroscopic studies of the electronic structure of conjugated polymer films; manipulating the interactions between polymer chains and fullerenes using using sequential processing and/or self-assembly techniques; studying the physics of carriers in working photovoltaic devices using a variety of transient current techniques; and studying the effects of different types of disorder using Drift-Diffusion simulations. This work provides students the opportunity to learn fundamental photophysics, polymer processing techniques, and semiconductor device construction.

 

Ten Representative Recent Publications

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R. C. Huber, A. S. Ferreira, R. Thompson, D. Kilbride, N. S. Knutson, L. Sudha Devi, D. B. Toso, J. Reddy Challa, Z. Hong Zhou, Y. Rubin, B. J. Schwartz and S. H. Tolbert, "Long-lived Photoinduced Polaron Formation in Conjugated Polyelectrolyte-Fullerene Assemblies," Science 348, 1340-3 (2015); DOI: 10.1126/science.aaa6850.

J. C. Aguirre, S. A. Hawks, A. S. Ferreira, P. Yee, S. Subramanyian, S. A. Jenekhe, S. H. Tolbert and B. J. Schwartz, "Sequential Processing for Organic Photovoltaics:  Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends," Adv. Energy Mater. 1402020, 1-11 (2015); DOI: 10.1002/aenm.201402020.

W. J. Glover, J. R. Casey and B. J. Schwartz, "Free Energies of Quantum Particles:  The Coupled-Perturbed Quantum Umbrella Sampling Method," J. Chem. Theor. Comput. 10, 4661-71 (2014); DOI: 10.1021/ct500661t.

J. C. Aguirre, C. Arnsten, S. Hernandez, R. Huber, A. M. Nardes, M. Halim, D. Kilbride, Y. Rubin, S. H. Tolbert, N. Kopidakis, B. J. Schwartz and D. Neuhauser, "Understanding Local and Macroscopic Electron Mobilities in the Fullerene Network of Conjugated Polymer-Based Solar Cells:  Time-Resolved Microwave Conductivity and Theory," Adv. Funct. Mater.  24(6), 784-92 (2014);  DOI: 10.1002/adfm.201301757.

J. R. Casey, R. E. Larsen and B. J. Schwartz, "Resonance Raman and Temperature-Dependent Electronic Absorption Spectra of Cavity and Non-Cavity Models of the Hydrated Electron," Proc. Nat. Acad. Sci. USA 110(8), 2712-7 (2013). 

S. C. Doan and B. J. Schwartz, "Nature of Excess Electrons in Polar Fluids:  Anion-Solvated Electron Equilibrium and Polarized Hole-Burning in Liquid Acetonitrile," J. Phys. Chem. Lett. 4, 1471-6 (2013). 

A. L. Ayzner, S. C. Doan, B. Tremolet de Villers and B. J. Schwartz, "Ultrafast Studies of Exciton Migration and Polaron Production in Sequentially Solution-Processed Conjugated Polymer/Fullerene Quasi-Bilayer Photovoltaics," J. Phys. Chem. Lett. 3, 2281-7 (2012). 

R. E. Larsen, W. J. Glover and B. J. Schwartz, "Does the Hydrated Electron Occupy a Cavity?," Science 329, 65 (2010).  See also the Technical Comments on this manuscript and our Response (Science 331, 1387-e (2011)).

A. E. Bragg, W. J. Glover and B. J. Schwartz, "Watching the Solvation of Atoms in Liquids One Solvent Molecule at a Time," Phys. Rev. Lett. 104, 233005, 1-4 (2010).

W. J. Glover, R. E. Larsen and B. J. Schwartz, "How does a Solvent Affect Chemical Bonds?  Mixed Quantum/Classical Simulations with a Full CI Treatment of the Bonding Electrons," J. Phys. Chem. Lett. 1, 165-9 (2010).


Complete Publication List  (including links to full text of papers) last updated 04/18/16.

 If you have problems viewing any of these papers (all in PDF format), try "Save Target As" instead of viewing directly through your browser.  
Contact Info

Department of Chemistry & Biochemistry
UCLA
Box 951569 (post)
607 Charles E. Young Drive East (courier)
Los Angeles, CA 90095-1569
 
 
Phone: (310) 206-4113
Fax: (310) 206-4038
Email: schwartz  at chem.ucla.edu

Student Office/Lab:  (310) 206-6418
 
Group

Current members of the Schwartz Group

The Schwartz group in May, 2016. 

Back row, from left to right:  Matt Fontana; Chen-Chen Zho; Ben Taggart; Ben Schwartz; Matthew Voss; Zongwu Fan; Godwin Kanu; Zach Gvildys
Front row, from left to right:  Erik Farr; Tyler Scholes; Taylor Aubry; Devon Widmer with Mei Widmer; Hannah Rodriguez

Not pictured:  Chien-Fu Huang

(for the Southpark version of the Schwartz group, click here). 
   

 Schwartz Group Photo Gallery

 Schwartz Group Press

 Evolution of the Schwartz Group
 
  Group Meeting Schedule

Please send comments on this page, notice of missing links, etc. to schwartz at chem.ucla.edu



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