Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 55: Inorganic/Organic Interfaces: Electronic Properties II

O 55.1: Hauptvortrag

Mittwoch, 18. März 2015, 15:00–15:30, HE 101

Electronic structure of Organo-Metal Halide Perovskites Films and Interfaces — •Antoine Kahn — Princeton University, Princeton, NJ, USA

This talk reviews direct and inverse photoemission data on the electronic structure of organo-metal halide perovskites, i.e., methylammonium lead tri-halides (MAPbX, X=Br3, I3, I3-xClx), and of their interfaces with hole- and electron-transport layers (HTL, ETL). Valence and conduction band edges of the MAPbX films, ionization energy and electron affinity (IE, EA) are determined [1]. Good alignment of the MAPbX conduction band minimum with that of the electron-collecting oxide is found, suggesting minimal energy loss during electron extraction at this interface. The hole-extraction interface is investigated for several HTLs. Results clearly puts into evidence the role of interface energetics in terms of carrier loss-less extraction or confinement in the perovskite layer [2]. The electronic structure of the inverted solar cell, with MAPbI3 on sol-gel processed NiOx, is also investigated [3]. The perovskite takes on a p-type character, indicative of a low density of deep gap states in the material. The NiOx/ MAPbI3 interface energetics provide barrier-free hole extraction (0.2 eV energy loss) and a high electron-blocking barrier. On the other side of the cell, C60 and derivatives form adequate ETLs, with neither a barrier for electron extraction nor a loss in accessible open circuit voltage.

[1] P. Schulz et al., Energ. & Envir. Sci. 7, 1377 (2014) [2] E. Edri et al., J. Phys. Chem. Lett., 5, 429 (2014) [3] P. Schulz et al. (under review)