Impact of N-Butylammonium Bromide on the Chemical and Electronic Structure of Double-Cation Perovskite Thin Films

Document Type

Article

Publication Date

11-10-2021

Publication Title

ACS Applied Materials and Interfaces

Volume

13

Issue

44

First page number:

53202

Last page number:

53210

Abstract

2D/3D perovskite heterostructures have emerged as a promising material composition to reduce nonradiative recombination in perovskite-based LEDs and solar cells. Such heterostructures can be created by a surface treatment with large organic cations, for example, n-butylammonium bromide (BABr). To understand the impact of the BABr surface treatment on the double-cation (Cs0.17FA0.83Pb(I0.6Br0.4)3) (FA = formamidinium) perovskite thin film and further optimize the corresponding structures, an in-depth understanding of the chemical and electronic properties of the involved surfaces, interfaces, and bulk is required. Hence, we study the impact of the BABr treatment with a combination of surface-sensitive X-ray photoelectron spectroscopy and bulk-sensitive resonant inelastic soft X-ray scattering (RIXS). A quantitative analysis of the BABr-treated perovskite thin film shows a modified chemical perovskite surface environment of carbon, nitrogen, bromine, iodine, and lead, indicating that the treatment leads to a perovskite surface with a modified composition and bonding structure. With K-edge RIXS, the local environment at the nitrogen and carbon atoms is probed, allowing us to identify the presence of BABr in the perovskite bulk albeit with a modified bonding environment. This, in turn, identifies a "hidden parameter"for the optimization of the BABr treatment and overall performance of 2D/3D perovskite solar cell absorbers.

Keywords

2D/3D perovskite heterostructure; n-butylammonium bromide surface treatment; perovskite-based solar cells; photoelectron spectroscopy; resonant inelastic soft X-ray scattering; X-ray absorption spectroscopy; X-ray emission spectroscopy

Disciplines

Chemical Engineering | Stars, Interstellar Medium and the Galaxy

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