Dresden 2017 – wissenschaftliches Programm
CPP 20.10: Vortrag
Dienstag, 21. März 2017, 12:15–12:30, ZEU 222
Towards a multiscale statistical description of hybrid perovskite materials — •Jingrui Li1, Jari Järvi1,2, and Patrick Rinke1 — 1COMP Centre of Excellence, Aalto University, Finland — 2Department of Physics, University of Helsinki, Finland
Hybrid perovskites (HPs), in particular methylammonium lead iodide (MAPbI3), have received enormous interest in recent years as promising photoactive materials in emergent photovoltaic technologies. An important feature of HPs is their structural complexity introduced by the organic cations (e.g., MA+). At room temperature or above, the MAs will be oriented (quasi-)randomly, forcing HPs into disordered structures. The disorder affects important materials properties such as the stability and electronic structure that are crucial for the application of HPs in novel photovoltaic devices. Our previous density-functional theory (DFT) study reveals that hydrogen bonding leads to an anisotropic interaction between the MA cations and the inorganic cage. The deformed cage and the MA orientation are interdependent, analogous to a chicken-and-egg paradox . From the insight of this single unit cell model, we derive a multiscale scheme for disordered MAPbI3 structures, in which the interaction between neighbouring MA ions is described by a pair model. We show that the total number of relevant pairs can be reduced to only 86 and then analyse DFT results for large, geometry optimized MAPbI3 supercell models in terms of their “pair-mode” distribution. With our model we can then describe disordered HPs on length scales beyond a few nanometers.
 J. Li and P. Rinke, Phys. Rev. B 94 045201 (2016).