Universität zu Köln

Rehermann, C., Schroder, V, Flatken, M., Uenlue, F., Shargaieva, O., Hoell, A., Merdasa, A., Mathies, F., Mathur, S. and Unger, E. L. (2022). Role of solution concentration in formation kinetics of bromide perovskite thin films during spin-coating monitored by optical in situ metrology. RSC Adv., 12 (50). S. 32765 - 32775. CAMBRIDGE: ROYAL SOC CHEMISTRY. ISSN 2046-2069

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Abstract

Optoelectronic devices based on metal halide perovskites continue to show a improved performance, and solution-based coating techniques pave the way for large-area applications. However, not all parameters influencing the thin film formation process of metal halide perovskites are identified and entirely rationalised over their full compositional range, thus hampering optimised thin film fabrication. Furthermore, while the perovskite deposition via spin-coating and annealing is an easily accessible technique, more profound insights into the chemical formation process are still lacking. Varying the precursor solution concentration is commonly used to vary the resulting thin film thickness. This study shows that varying the precursor solution concentration also affects the thin film morphology and optoelectronic quality. Hence, we herein investigate the influence of the precursor solution concentration on the formation process of a pure bromide-based triple cation perovskite (Cs(0.05)MA(0.10)FA(0.85)PbBr(3)) by fiber-based optical in situ measurement. During the spin-coating process, in situ UV-vis and PL measurements reveal formation kinetics are strongly dependent on the concentration. Furthermore, we identify delayed nucleation and retarded growth kinetics for more concentrated precursor solutions. In addition, we quantify the shifting chemical equilibrium of colloidal pre-coordination in the precursor solution depending on concentration. Namely, colloids are pre-organised to a higher degree and higher-coordination lead-bromide complexes tend to form in more concentrated precursor solutions. Thus, the modified solution chemistry rationalises retarded perovskite formation kinetics and highlights the precursor concentration as an influential and optimisable parameter for solution-based thin film deposition.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Rehermann, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schroder, V UNSPECIFIED UNSPECIFIED UNSPECIFIED Flatken, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Uenlue, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Shargaieva, O. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hoell, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Merdasa, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mathies, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mathur, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Unger, E. L. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-682455
DOI:	10.1039/d2ra06314j
Journal or Publication Title:	RSC Adv.
Volume:	12
Number:	50
Page Range:	S. 32765 - 32775
Date:	2022
Publisher:	ROYAL SOC CHEMISTRY
Place of Publication:	CAMBRIDGE
ISSN:	2046-2069
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SOLAR-CELLS; SCALABLE FABRICATION; CRYSTALLIZATION; EFFICIENCY; MORPHOLOGY; CHLORIDE Multiple languages Chemistry, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/68245