Materials Science Seminar Presents: Noa Marom, University of Texas, Austin

Dr. Noa Marom University of Texas, Austin

Tuesday, May 15, 2012 (please note the day change) 4:00 P.M. 106 Spalding

Refreshments will be served at 3:45 p.m. in 102 Spalding

Electronic Structure of Dye-Sensitized TiO2 Clusters from Many-Body Perturbation Theory

The development of new types of solar cells is driven by the need for clean and sustainable energy. In this respect dye sensitized solar cells (DSC) are considered as a promising route for departing from the traditional solid state cells. The physical insight provided by computational modeling may help develop improved DSCs. To this end it is important to obtain an accurate description of the electronic structure, including the fundamental gaps and level alignment at the dye-TiO2 interface. This requires a treatment beyond ground-state density functional theory (DFT).

Presented in this talk will be a many-body perturbation theory study of TiO2 clusters, dye molecules, and dye-sensitized TiO2 clusters, within the G0W0 approximation. At this level of approximation the one-particle Green's function, G, and the screened Coulomb interaction, W, are calculated non-self-consistently, based on DFT orbitals and eigenvalues. G0W0 calculations, based on a hybrid functional, are in excellent agreement with photoemission spectroscopy (PES) experiments. For TiO2 clusters, this enables the identification of the isomers observed in PES as those with the highest vertical electron affinity [1]. For transition metal phthalocyanine dyes, unlike DFT, G0W0 calculations correctly predict the energies of orbitals associated with the metal d-states [2]. For dye-sensitized TiO2 clusters, G0W0 calculations provide reliable predictions for the fundamental gaps and the level alignment at the dye-TiO2 interface [3].

References: [1] Phys. Rev. Lett. 108, 106801 (2012), [2] Phys. Rev. B 84, 195143 (2011), [3] Phys. Rev. B 84, 245115 (2011)

More about the Speaker Dr. Noa Marom: Noa Marom is currently a postdoctoral fellow at the University of Texas at Austin. She received a PhD in 2010 at the Weizmann Institute of Science in Israel and a BS degree in Materials Engineering and BA in Physics in 2002 at Technion, Israel Institute of Technology.