Condensed Matter Seminar: "The Structure and Function of Organic-Inorganic Hybrid Perovskites"

Wed, 10/25/2017 - 16:00 - 17:00
Cherie Kagan (University of Pennsylvania)

Organic-inorganic hybrid perovskites represent a class of materials composed of corner sharing metal halide octahedra charge balanced by organic cations. The hybrid perovskites may be tailored in their composition and in their dimensionality. Research exploring hybrid perovskites skyrocketed in the past few years because of the remarkable, >20% power conversion efficiency demonstrated for the three-dimensional (3D) lead halide structures in solar cells, which currently rivals that of commercial silicon-based solar cells. While work continues to boost solar cell performance at a furious pace and to explore stable and non-toxic compositions, important for commercialization, this fever has brought renewed attention to the physics and chemistry of two-dimensional (2D) hybrid perovskites. The 2D perovskites are solution-processable, multi-layered materials, which adopt the Ruddlesen-Popper structure, and exhibit strong quantum and dielectric confinement effects, forming “perfect” quantum well superlattices. Here, I will review the fundamental structural and optical and electronic properties of 3D and 2D perovskites. I will also share recent work from our group exploring the photophysics of 2D perovskites, which shows strong electron-phonon coupling and hot exciton emission, due to relatively slow vibrational relaxation.1 Our studies are consistent with the picture of large polaron formation in this materials class. Finally, I will describe future research directions and applications for this versatile materials class.

(1)         Straus, D. B.; Hurtado Parra, S.; Iotov, N.; Gebhardt, J.; Rappe, A. M.; Subotnik, J. E.; Kikkawa, J. M.; Kagan, C. R. J. Am. Chem. Soc. 2016, 138 (42), 13798–13801.

David Rittenhouse Laboratory, A4