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Lookup NU author(s): Dr Pablo Docampo
This is the authors' accepted manuscript of an article that has been published in its final definitive form by Royal Society of Chemistry, 2018.
For re-use rights please refer to the publisher's terms and conditions.
Two-dimensional (2D) hybrid perovskites have attracted considerable attention due to their enormous structural and electronical variability, making this class of semiconductors interesting for photovoltaics, light-emitting diodes and lasers. 2D perovskites consist of sheets of bulky organic cations alternately sandwiched by layers of lead halide octahedra. The properties of these materials strongly depend on the thickness of the octahedra layers, defined by the number of octahedra sheets in a layer, n. Consequently, controlling the layer thickness purity (i.e. minimizing the spread in n) is important for any 2D perovskite thin film application. Here, we show that using rationally chosen solvent additives in the precursor solution offers a facile way to control the crystal disorder in 2D perovskites films. Our method leads to significantly reduced variation in n around the target value relative to films obtained by conventional fast-crystallization methods without solvent additives. The improved phase purity in optimized n = 2 and n = 3 films is verified by X-ray diffraction, UV-Vis absorption, and photoluminescence measurements. Additionally, we find that 2D perovskite films with n³ 2 arising from additive-assisted growth exhibit an unusual crystal orientation with the perovskite interlayers predominantly aligned parallel to the substrate, which we assign to the slow crystallization process induced by the lead-complexing solvent additives. Improved control over the phase purity translates into a better control of the optoelectronic properties of 2D perovskite films. Furthermore, the unusual horizontal crystal orientation of n = 2 and n = 3 films makes this family of tunable organic-inorganic perovskites promising for applications where lateral charge transport is desired, thus enlarging the potential for thin film-based applications of the 2D perovskites.
Author(s): Hu Y, Spies LM, Alonso-Alvarez D, Mocherla P, Jones H, Hanisch J, Bein T, Barnes PRF, Docampo P
Publication type: Article
Publication status: Published
Journal: Journal of Materials Chemistry A
Print publication date: 28/11/2018
Online publication date: 31/08/2018
Acceptance date: 28/08/2018
Date deposited: 04/09/2018
ISSN (print): 2050-7488
ISSN (electronic): 2050-7496
Publisher: Royal Society of Chemistry
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