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Al 2 O 3 ‐Atomic Layer Deposited Films on CH 3 NH 3 PbI 3 : Intrinsic Defects and Passivation Mechanisms
Author(s) -
Kot Małgorzata,
Henkel Karsten,
Müller Klaus,
Kegelmann Lukas,
Albrecht Steve,
Tsud Nataliya,
Kús Peter,
Matolinová Iva,
Schmeißer Dieter
Publication year - 2019
Publication title -
energy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 44
eISSN - 2194-4296
pISSN - 2194-4288
DOI - 10.1002/ente.201900975
Subject(s) - x ray photoelectron spectroscopy , materials science , substrate (aquarium) , grain boundary , passivation , polaron , layer (electronics) , crystallography , exciton , charge (physics) , condensed matter physics , nanotechnology , chemistry , electron , chemical engineering , metallurgy , microstructure , oceanography , physics , quantum mechanics , engineering , geology
The initial interaction of atomic layer deposited films of Al 2 O 3 at room temperature on CH 3 NH 3 PbI 3 (MAPI) films is studied. Synchrotron radiation–based photoelectron spectroscopy is applied to analyze the initial changes in the Al‐derived features by comparing samples with different Al 2 O 3 film thicknesses. It is found that polarons and excitons, both intrinsic defects of Al 2 O 3 , play a key role in the interface formation. The polaronic states uptake a charge from the MAPI substrate. This charge is transferred to and stabilized in the excitonic state of Al 2 O 3 which is assigned to predominately tetrahedral coordinated Al sites. This charge transfer is initiated by vacancies present in the MAPI substrate and stabilizes a covalent bonding at the Al 2 O 3 –MAPI interface but also causes a roughening of the interface which may lead to the formation of grain boundaries. On top of the rough interface, 2D Al 2 O 3 clusters with an increasing number of octahedrally coordinated Al—O bonds grow, and with increasing Al 2 O 3 coverage, they introduce self‐healing of the structural defects.