MRI SEMINAR Prof. Prof. Laura Herz, University of Oxford - Hybrid Metal Halide Perovskites for Photovoltaics: Optoelectronic Properties and Stability
Date: 4 October 2017 Time: 15:00 - 16:00
Hybrid metal halide perovskites (stoichiometry AMX3) have recently emerged as low-cost active materials in PV cells with power conversion efficiencies in excess of 21%. We discuss how optoelectronic properties essential for photovoltaic operation, such as crystallinity, photostability, charge carrier mobility, recombination and diffusion lengths are altered with substitutions of the organic A cation (e.g. methylammonium versus formamidinium), the metal M cation (e.g. Pb2+ or Sn2+) and the halide X anion (I- versus Br-). We focus on two 3D perovskite systems that have attracted much interest lately, lead-free ASnI3 (optical bandgap ~1.3 eV) and the mixed organic lead iodide/bromide system APb(BryI1-y)3 whose band gap can be tailored between ~1.5 eV (FAPbI3) and ~2.3 eV (FAPbBr3). We show that unintentional hole doping in tin iodide perovskites introduces fast recombination pathways that can be moderated by crystal structure  and introduces a radiative quasi-monomolecular charge recombination channel . In addition, we examine mixed-halide perovskites with band gap near 1.7eV, ideal for use in two-terminal tandems with silicon bottom cells. We demonstrate that charge-carrier diffusion and recombination in FA1-xCsxPb(BryI1-y)3 can be optimised for high performance that depends on a complex interplay between changes in morphology and electronic bandstructure with bromide fraction y [3,4,5].
 Parrott, Milot, Stergiopoulos, Snaith, Johnston, Herz, J. Phys. Chem. Lett. 7, 1321 (2016).
 Milot, Eperon, Green, Snaith, Johnston, Herz, J. Phys. Chem. Lett. 7, 4178 (2016).
 Rehman, Milot, Eperon, Wehrenfennig, Boland, Snaith, Johnston, Herz, Adv. Mater. 27, 7938 (2015).
 McMeekin, Sadoughi, Rehman, Eperon, Saliba, Hörantner, Haghighirad, Sakai, Korte, Rech, Johnston, Herz, Snaith, Science 351, 151 (2016).
 Rehman, McMeekin, Patel, Milot, Johnston, Snaith, Herz, Energy Environ. Sci. 10, 361 (2017).
|Location:||David Sizer Theatre|