Le séminaire Electronic Structure of Hybrid Organic Inorganic Perovskites Interfaces se déroulera en anglais seulement.

Entrée libre

Bienvenue à tous!

Antoine Kahn
Department of Electrical Engineering,
Princeton University, Princeton, USA

Electronic Structure of Hybrid Organic Inorganic Perovskites Interfaces

Hybrid Organic Inorganic Perovskites (HOIP) have recently led to stunningly rapid progress on the photovoltaic scene. HOIP solar cells include key interfaces with organic and inorganic electron and hole transport layers (ETL, HTL), which must be carefully optimized in order to insure high efficiency devices. This talk first reviews recent work on the determination of the electronic structure of HOIPs, specifically methylammonium lead halides (MAPbX, X=Br3, I3, I3-xClx) and tin halides, with evaluation of their valence and conduction band edges, ionization energy and electron affinity (IE, EA) [1]. We then turn to HOIP interfaces, which play a central role for efficient electron and hole extraction. The electronic structure of several TiO2/HOIP/organic HTL “conventional” cells, and NiOx/HOIP/organic ETL “inverted” cells are given. Results put in evidence the role of interface energetics in terms of carrier loss-less extraction from, or confinement in, the perovskite layer [2]. The shift of the HOIP Fermi level from the top of the gap in TiO2/HOIP to the lower half of the gap in NiOx/HOIP [3] is discussed for its implications in terms of density of gap states in these materials. Finally, we discuss the damaging chemistry, which takes place at the interface between MAPbI3 and the high work function HTL MoO3, and its eventual mitigation with an ultra-thin organic buffer layer.

[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., Adv. Mat. Interf. (2015) DOI: 10.1002/admi.201400532