A photoelectron spectroscopy investigation of the electronic and chemical structure profile of the interface between ALD processed SnO2 and metal halide perovskite
Perovskite solar cells (PSCs) have recently exceeded 25% conversion efficiencies approaching the single-cell efficiency limit. However, there is still room for improvements. Specifically, the stability and performance of perovskite solar cells can be related to the chemistry of the interfaces between the perovskite absorber and the charge transport layers (CTLs). In this view, replacing the currently used organic CTLs, which introduce optical parasitic absorption, shunting pathways and have poor mechanical properties, for inorganic based CTL could further improve the performance of PSCs. However, when a thin film deposition technique such as atomic layer deposition (ALD) is used to grow the electron transport layer directly on the absorber, it induces chemical modifications which lead to poor performing devices. In this study, we are going to evaluate the electronic and chemical profile of the interface between the ALD-grown SnO2 and a Cs0.15FA0.85Pb(I0.92Br0.08)3 perovskite absorber.
Status: Ongoing
Date of proposal: 03/12/2021
Start date: 07/04/2022
End Date: 20/04/2022
Used Instruments: XPS, UPS, IPES facilities at Helmholtz-Zentrum Berlin fr Materialien und Energie (HZB).
Experimental Technique: X-Ray Photoelectron Spectroscopy (XPS). UV Photoelectron Spectroscopy (UPS). Inverse Photoemission Spectroscopy (IPES).
Experiment Description: Investigation of the electronic and chemical structure profile at the interface between ALD processed SnO2 and metal halide perovskite, particularly focusing on the effects of different thicknesses of SnO2 on the perovskite absorber layer.
Type Samples: SnO2/Perovskite interface samples with varying thicknesses of SnO2.
Sample Description: Samples with different SnO2 thicknesses (5, 10, 20, and 40 nm) on the perovskite absorber layer, along with reference samples, were prepared by the Plasma and Materials Processing group at Eindhoven University of Technology.
Experiment Data Type: XPS, UPS, and IPES spectra showing the electronic and chemical profiles of the SnO2/perovskite interface.
Characterization Technics: Photoelectron spectroscopy techniques (XPS, UPS, IPES) to analyze the surface chemistry and electronic structure of the samples.
Characterization Data Type: Chemical and electronic structure profiles of the interfaces. Core level spectra for elements like I, Pb, and Sn.
Analyzed Data: Analysis of the impact of SnO2 thickness on the perovskite absorber layer. Observation of changes in energy shifts and line shapes in core level spectra, possibly due to interactions between SnO2 and the perovskite layer.
Main Targets Project: Evaluating the influence of the ALD-grown SnO2 electron transport layer (ETL) on the chemical and electronic properties of the perovskite absorber layer. Understanding the interface properties for improved perovskite solar cell performance.
Main Achievements Findings: Identification of dominant photoelectron doublet peaks of the perovskite layer even with increasing SnO2 thickness, indicating possible incomplete coverage or diffusion issues. Detection of changes in energy shifts and line shapes in core level spectra, suggesting potential effects on the perovskite layer due to ALD process conditions or electronic structure alterations.
Review 7
How would you describe your experience with the VIPERLAB opportunity? How did the experience/visit at EMIL lab meet your expectations?
I did not directly travel to the EMIL lab to carry out the measurements. The data was collected by the co-authors of the project submission as part of the collaboration.
Did you face any difficulties during your visit or application process?
Nothing specific, possibly only figuring out which lab to apply to, but this was taken care by the co-authors of the project.
Does this VIPERLAB experience at EMIL lab bring you closer to your research objectives? How?
The data was not sufficient to draw scientific conclusions strong enough to support my ongoing research.
What other VIPERLAB activities have you participated in, or would you like to participate in?
Do you intend or already did publish/present your collected results in a paper or conference?
At the moment, we are working on publishing the results. The data has been partially presented at the Tandem PV Workshop held in 2022 and during a poster session at the school on UV and x-ray spectroscopies of correlated electron systems (SUCCESS) in 2022.