Universität zu Köln

Shallcross, R. Clayton ORCID: 0000-0003-3167-4801, Olthof, Selina ORCID: 0000-0002-8871-1549, Meerholz, Klaus ORCID: 0000-0001-7450-4672 and Armstrong, Neal R. (2019). Impact of Titanium Dioxide Surface Defects on the Interfacial Composition and Energetics of Evaporated Perovskite Active Layers. ACS Appl. Mater. Interfaces, 11 (35). S. 32500 - 32509. WASHINGTON: AMER CHEMICAL SOC. ISSN 1944-8252

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Abstract

This investigation elucidates critical Bronsted and Lewis acid-base interactions at the titanium dioxide (TiO2) surface that control the interfacial composition and, thus, the energetics of vacuum-processed methylammonium lead iodide (MAPbI(3)) perovskite active layers (PALs). In situ photoelectron spectroscopy analysis shows that interfacial growth, chemical composition, and energetics of co-deposited methylammonium iodide (MAI)/PbI2 thin films are significantly different on bare and (3-aminopropyl)triethoxysilane (APTES)-functionalized TiO2 surfaces. Mass spectroscopy analysis indicates that MAI dissociates into hydrogen iodide and methylamine in the gas phase and suggests that MAPbI(3) nucleation is preceded by adsorption and coupling of these volatile MAI precursors. Prior to MAPbI(3) nucleation on the bare TiO2 surface, we suggest that high coverages of methylamine adsorbed to surface defect sites (e.g., undercoordinated Ti atoms and hydroxyls) promote island-like growth of large, PbI2-rich nuclei that inhibit nucleation and lead to a thick substoichiometric interface layer that impedes charge transport and collection energetics. APTES functional groups passivate TiO2 surface defects and facilitate more conformal growth of small, PbI2-rich nuclei that enhance MAPbI(3) nucleation and significantly improve interfacial energetics for charge transport and extraction. This work highlights the considerable influence of TiO2 surface chemistry on PAL composition and energetics, which are critical factors that impact the performance and long stability of these materials in emerging photovoltaic device technologies.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Shallcross, R. Clayton UNSPECIFIED orcid.org/0000-0003-3167-4801 UNSPECIFIED Olthof, Selina UNSPECIFIED orcid.org/0000-0002-8871-1549 UNSPECIFIED Meerholz, Klaus UNSPECIFIED orcid.org/0000-0001-7450-4672 UNSPECIFIED Armstrong, Neal R. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-141738
DOI:	10.1021/acsami.9b09935
Journal or Publication Title:	ACS Appl. Mater. Interfaces
Volume:	11
Number:	35
Page Range:	S. 32500 - 32509
Date:	2019
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	1944-8252
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Physical Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SOLAR-CELLS; PHOTOELECTRON-SPECTROSCOPY; ADSORPTION; ENERGY; PHASE; STOICHIOMETRY; DEGRADATION; EFFICIENT; ALIGNMENT; TIO2 Multiple languages Nanoscience & Nanotechnology; Materials Science, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/14173