Dresden 2017 – wissenschaftliches Programm
CPP 3.6: Vortrag
Montag, 20. März 2017, 12:00–12:15, ZEU 222
Effect of Thermal and Structural disorder on Electronic Structure in Methylammonium Lead Halide Perovskites — •Cheng Li1, Shivam Singh2, Fabian Panzer3, K L. Narasimhan2, Yu Zhong1, Anna Gräser1, Tanaji Gujar1, Mukundan Thelakkat1, Anna Köhler3, Dinesh Kabra2, and Sven Huettner1 — 1Macromolecular Chemistry I, Universität Bayreuth, Universitätstr. 30, 95447 Bayreuth, Germany — 2Indian Institute of Technology Bombay, Powai, 400076 Mumbai, Indian — 3Experimentalphysik II, Universität Bayreuth, Universitätstr. 30, 95447 Bayreuth, Germany
In this work, to understand the structure of perovskite materials, we investigate the temperature dependence of optical properties of perovskite from room temperature (300K) to 6K. Unlike typical inorganic semiconductor, in both tetragonal (T>163K) and orthorhombic (T<163K) phases of MAPbI3, the band gap decreases with decrease in temperature. We indicate that this temperature dependence of the band gap is governed by the lattice expansion term instead of the electron-phonon interaction. The exciton linewidth is homogeneously broadened in both phases. The absorption, at the low energy edge of the exciton absorption, increases exponentially with energy, i.e reminiscent of Urbach tail absorption. The Urbach energy which is used to characterize order of structure, is modelled using thermal and static disorder for both phases separately.This work provides important insights to the electronic and structural properties of MAPbI3 based perovskites, and this method is transferable to many related perovskites.