Gregory Scholes

Academic Title: Associate Professor

Phone: 416-946-7532

Office: LM 241

Email:

Research Homepage: http://www.chem.utoronto.ca/staff/SCHOLES/scholes_home.html

Nanoscale systems are forecast to be a means of integrating desirable attributes of both molecular and bulk materials into easily processed materials. Such materials would be used to make affordable technologies and even new kinds of devices to enrich our lives. Notable examples include plastic full-colour displays, electronic clothing, lasers that can transmit information rapidly within a supercomputer, and organic solar cells to produce affordable renewable energy. The development, operation, and improvement of these kinds of emerging technologies hinge on us being able to control molecular-scale events that emit light or are initiated by light. The projects that teams of students and postdocs in the Scholes Group are presently working on include:

(a) Quantum effects in biology. Recent discoveries in our group and at UC Berkeley suggest that light-harvesting in some photosynthetic proteins involves quantum-coherence. This has captured the attention of researches for several reasons. First, it means that quantum mechanical probability laws can prevail over the classical laws of kinetics, allowing the possibility that light-initiated processes can by controlled using the interference principles first described by Schrödinger, Dirac, Feynman, and others. Second, it raises the fascinating question: have these organisms developed quantum-mechanical strategies for light-harvesting to gain an evolutionary advantage? That is, did algae know about quantum mechanics two billion years before mankind?!

(b) Charge transfer in semiconductor nanocrystal heterostructures and applications in solar cells. Much is known about electron transfer reactions in supramolecular systems, but hardly anything is known about nanoscale analogs. We are designing, synthesizing, and studying light-initiated charge transfer reactions in sophisticated nanocrystal heterostructures.

(c) Ultrafast energy transfer in conjugated polymers. After our recent discovery of room-temperature quantum-coherent energy transfer along a conjugated polymer chain we aim to work out how to put that to use to increase the distance over which excitation energy can migrate in organic solar cells.

(d) The theory of electronic energy transfer. Despite a century of study, researchers are still learning about basic physical chemistry by studying how the energy of absorbed light hops from one molecule to another. Our studies range from examining how proteins influence energy transfer at an atomic level of detail to the development of fundamental physical models that help us address questions basic to quantum-mechanics and quantum information science.

(e) Gaining insight into reaction mechanisms in organic chemistry by learning how to watch the collective quantum-mechanical changes in electron motions using new coherent multidimensional laser spectroscopy.

Gregory D. Scholes & Garry Rumbles, Excitons in Nanoscale Systems, Nature Materials 5, 683-696 (2006).

Elisabetta Collini & Gregory D. Scholes, "Quantum coherent energy migration in a conjugated polymer at room temperature" Science 323, 369-373 (2009).

Marcus Jones, Shun S. Lo, & Gregory D. Scholes, "Quantitative modeling of the role of surface traps in CdSe/CdS/ZnS nanocrystal photoluminescence decay dynamics" Proc. Natl. Acad. Sci. USA 106, 3011-3016 (2009).

Jeongho Kim, Cathy Y. Wong & Gregory D. Scholes, "Exciton Fine Structure and Spin Relaxation in Semiconductor Colloidal Quantum Dots" Acc. Chem. Res. (in press, 2009): DOI: 10.1021/ar8002046.

Jeongho Kim, Shaul Mukamel and Gregory D. Scholes, "Two-dimensional Electronic Double-Quantum Coherence Spectroscopy" Acc. Chem. Res., Special Issue on Multidimensional Spectroscopy DOI: 10.1021/ar9000795 (in press, 2009).

Haizheng Zhong and Gregory D. Scholes, "Shape Tuning of Type II CdTe-CdSe Colloidal Nanocrystal Heterostructures through Seeded Growth" J. Am. Chem. Soc. (Commun.) 131, 9170-9191 (2009).

David Beljonne, Carles Curutchet, Gregory D. Scholes and Robert Silbey, "Beyond Förster resonance energy transfer in biological and nanoscale systems" J. Phys. Chem. B Feature Article 113, 6583-6599 (2009).

Graham R. Fleming and Gregory D. Scholes, Quantum mechanics for plants, Nature, 431, 256 (2004).

Gregory D. Scholes, Long range resonance energy transfer in molecular systems, Annu. Rev. Phys. Chem. 54, 57-87 (2003).