Regensburg 2016 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 11: Poster: Hybrid and Perovskite Photovoltaics
CPP 11.21: Poster
Montag, 7. März 2016, 18:15–21:00, Poster B2
Effect of Thermal and Structural disorder on Electronic Structure of Hybrid Perovskite Semiconductor CH3NH3PbI3 — Cheng Li1, Shivam Singh2, K. L. Narasimhan2, Fabian Panzer3, Tanaji Gujar4, Mukundan Thelakkat4, Anna Köhler3, Dinesh Kabra2, and •Sven Hüttner1 — 1Organic and Hybrid Electronics, Makromol. Chemie I, Universität Bayreuth — 2Indian Institute of Technology Bombay, Powai, Mumbai — 3Experimentalphysik II, Universität Bayreuth — 4Angew. Funktionspolymere, Makromol. Chemie I, Universität Bayreuth
We investigate the temperature dependence of optical properties of methylamonimum lead iodide (MAPbI3 = CH3NH3PbI3) from room temperature to 6K. In both tetragonal (T> 163K) and orthorhombic (T<163K) phases of MAPbI3, the band gap decreases with decrease in temperature in contrast to what is normally seen for many inorganic semiconductors. We show that the temperature dependence of the band gap is determined by the lattice expansion term rather than 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 - reminiscent of Urbach tail absorption. The Urbach energy is a measure of the disorder, which is modelled using thermal and static disorder for both the phases separately. The static disorder component is small, which is consistent with the observed homogeneous broadening of the exciton with temperature. Both these features are a measure of the high crystal quality of the perovskite films.