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Cathy Wong

Cathy Wong profile picture
  • Affiliation: faculty
  • Title: Assistant Professor
  • Phone: 541-346-7323
  • Office: 143 Klamath Hall
  • Website: Website

Education

B.Sc. McMaster University, Biological Chemistry (2004, Johan Terlouw)
Ph.D. University of Toronto, Physical Chemistry (2011, Greg Scholes)
Postdoc UC Berkeley (2015, Naomi Ginsberg)

 

Research

Photovoltaic and optoelectronic materials are often assembled from nanoscale building blocks, such as small organic molecules, quantum dots, or polymers. Different methods can be used to put these building blocks together, but one of the most common and cost-effective methods is deposition from a solution. As solvent evaporates, the individual building blocks get closer together, start to interact, and end up in particular physical arrangements. As components of a system couple together, these physical arrangements can result in disorder and defects, and the group of particles can exhibit collective phenomena that alter the behavior of excitons and carriers in unexpected ways.
Research in our lab seeks to adapt time-resolved exciton spectroscopies to the measurement of nanoscale building blocks during their self-assembly. We will measure electronic structure and exciton dynamics in situ and in real-time as irreversible processes occur, such as crystallization, self-assembly, and chemical bond formation. By measuring and comparing how exciton behavior changes during self-assembly using various solution deposition techniques, we develop strategies to control self-assembly to create materials with designer excitonic properties.
 
We have developed a single-shot transient absorption spectrometer that allows us to measure exciton dynamics in situ during materials formation and other non-equilibrium processes. Transient absorption uses an ultrafast laser pulse to ‘pump’ the sample, creating excited states, then a second laser pulse after a controlled delay time to ‘probe’ the sample. By changing the delay time, we can measure the dynamics of the excited states. We use tilted beams to spatially encode the time delay in our sample, allowing us to measure the dynamics in a single shot, dramatically decreasing the time needed to complete a measurement. This allows us to measure systems that are changing in time, like aggregating organic molecules, or crystallizing perovskites. Our technique can provide insight into the complex processes involved in materials formation, and will show us how we can steer materials to have particular excited state dynamics by changing environmental conditions while the material is being made. We are continually developing and improving the design of our instruments and building new reaction chambers and film deposition stages so we can measure materials formation in our laser lab, and provide valuable feedback for rational materials design.

Publications

  1. K.S. Wilson and C.Y. Wong (2018) Single-shot transient absorption spectroscopy with a 45 ps pump-probe time delay range. Opt. Lett. 43: 371-374.
  2. K.S. Wilson and C.Y. Wong (2017) Calibrating a spatially encoded time delay for transient absorption spectroscopy. Proc. SPIE 10348, Physical Chemistry of Semiconductor Materials and Interfaces XVI 1034805.
  3. C.Y. Wong, B.D. Folie, B.L. Cotts, N.S. Ginsberg (2015) Discerning Variable Extents of Interdomain Orientational and Structural Heterogeneity in Solution-Cast Polycrystalline Organic Semiconducting Thin Films. J. Phys. Chem. Lett. 6: 3155-3162.
  4. C.Y. Wong, B.L. Cotts, H. Wu and N.S. Ginsberg (2015) Exciton dynamics reveal aggregates with intermolecular order at hidden interfaces in solution-cast organic semiconducting films. Nat. Commun. 6: 5946.
  5. S. Sharifzadeh, C.Y. Wong, H. Wu, B.L. Cotts, L. Kronik, N.S. Ginsberg and J.B. Neaton (2015) Relating the physical structure and optoelectronic function of crystalline TIPS-pentacene. Adv. Funct. Mater. 25: 2038-2046.
  6. C.Y. Wong, S.B. Penwell, B.L. Cotts, R. Noriega, H. Wu and N.S. Ginsberg (2013) Revealing exciton dynamics in a small-molecule organic semiconducting film with subdomain transient absorption microscopy. J. Phys. Chem. C 117: 22111-22122.
  7. C.Y. Wong, R.M. Alvey, D.B. Turner, K.E. Wilk, D.A. Bryant, P.M.G. Curmi, R.J. Silbey and G.D. Scholes (2012) Electronic coherence lineshapes reveal hidden excitonic correlations in photosynthetic light harvesting. Nat. Chem. 4: 396-404.
  8. M.H.J. Oh, M.R. Salvador, C.Y. Wong and G.D. Scholes (2011) Three-pulse photon-echo peak shift spectroscopy and its application for the study of salvation and nanoscale excitons. ChemPhysChem 12: 88-100.
  9. C.Y. Wong and G.D. Scholes (2010) Biexcitonic fine structure of CdSe nanocrystals probed by polarization dependent two-dimensional photon echo spectroscopy. J. Phys. Chem. A 115: 3797-3806.
  10. C.Y. Wong and G.D. Scholes (2010) Using two-dimensional photon echo spectroscopy to probe the fine structure of the ground state biexciton of CdSe nanocrystals. J. Luminesc. 131: 366-374.
  11. E. Collini,* C.Y. Wong,* K.E. Wilk, P.M.G. Curmi, P. Brumer and G.D. Scholes (2010) Coherently wired light-harvesting in photosynthetic marine algae and ambient temperature. Nature 463: 644-647.
  12. J. Kim, C.Y. Wong and G.D. Scholes (2009) Exciton fine structure and spin relaxation in semiconductor colloidal quantum dots. Acc. Chem. Res. 42: 1037-1046.
  13. C.Y. Wong, C. Curutchet, S. Tretiak and G.D. Scholes (2008) Ideal dipole approximation fails to predict electronic coupling and energy transfer between semiconducting single-wall carbon nanotubes. J. Chem. Phys. 130: 081104.
  14. C.Y. Wong,* J. Kim,* P.S. Nair, M.C. Nagy and G.D. Scholes (2008) Relaxation in the exciton fine structure of semiconductor nanocrystals. J. Phys. Chem. C 113: 795-811.
  15. J. Kim, P.S. Nair, C.Y. Wong and G.D. Scholes (2007) Sizing up the exciton in complex shaped semiconductor nanocrystals. Nano Lett. 7: 3884-3890.
  16. J. Kim, C.Y. Wong, P.S. Nair, K.P. Fritz, S. Kumar and G.D. Scholes (2006) Mechanism and origin of exciton spin relaxation in CdSe nanorods. J. Phys. Chem. B 110: 25371-25382.
  17. G.D. Scholes, J. Kim, C.Y. Wong, V.M. Huxter, P.S. Nair, K.P. Fritz and S. Kumar (2006) Nanocrystal shape and the mechanism of exciton spin relaxation. Nano Lett. 6: 1765-1771.
  18. G.D. Scholes, J. Kim and C.Y. Wong (2006) Exciton spin relaxation in quantum dots measured using ultrafast transient polarization grating spectroscopy. Phys. Rev. B 73: 195325.
  19. C.Y. Wong, P.J.A. Ruttink, P.C. Burgers and J.K. Terlouw (2004) The isomerization of [H2O-C=O]•+ and [HC(=O)OH]•+ into [HO-C-OH]•+: proton-transport catalysis by CO. Chem. Phys. Lett. 390: 176-180.
  20. C.Y. Wong, P.J.A. Ruttink, P.C. Burgers and J.K. Terlouw (2004) The ionic isomerization [HCOH]•+ - [CH2=O]•+: proton-transport catalysis by CO and CO2. Chem. Phys. Lett. 387: 204-208.
  21. R. Srikanth, K. Bhanuprakash, R. Srinivas, C.Y. Wong and J.K. Terlouw (2004) Protonated silanoic acid HSi(OH)2+ and its neutral counterpart: a tandem mass spectrometric and CBS-QB3 computational study. J. Mass Spectrom. 39: 303-311.
  22. L.N. Heydorn, C.Y. Wong, R. Srinivas and J.K. Terlouw (2003) The isobaric ions CH3O-P=O•+ and CH3O-P-NH2+ and their neutral counterparts: A tandem mass spectrometry and CBS-QB3 computational study. Int. J. Mass Spectrom. 225: 11-23.