Understanding and overcoming the fundamental chemical and electronic challenges of snBr₄ impurities in tin perovskite solar cells
Author(s)
Type
Journal Article
Abstract
Tin perovskite solar cells (Sn-PSCs) have emerged as excellent candidates for nontoxic narrow bandgap PSCs. Nevertheless, the technology remains limited by both stability and suboptimal energetic alignment with conventional charge transport layers. Compositional tuning is central to high-performance Sn-PSCs, replacing substoichiometric iodide ions with bromide. However, incorporating SnBr2 as the bromide source introduces SnBr4 impurities, underscoring the need to understand the consequences of SnBr4 on both performance and degradation chemistry. Presently, the absence of such understanding has engendered a reliance on organobromide salts, neglecting a critical opportunity to enhance stability via the reduction of unstable SnI2. Herein, the influence of SnBr4 impurities on the structural, optoelectronic, and electronic properties of Sn-perovskites is investigated. Removal of SnBr4 impurities from SnBr2 results in drastically improved morphology, a 40% lower trap density and enhanced device performance of 150%. Furthermore, both the fundamental chemistry and degradation pathways in SnI4 and SnBr4 are compared, demonstrating the latter does not decompose to the molecular halogen—a key weakness of iodine-based Sn-PSCs. The present findings offer critical chemical and electronic insights into the presence of SnBr4, the importance of its removal and the opportunities afforded by using SnBr2 to minimize unstable SnI2 in Br-rich Sn-perovskite phases.
Date Issued
2025-12-01
Date Acceptance
2025-11-01
Citation
Small Science, 2025, 5 (12)
ISSN
2688-4046
Publisher
Wiley-VCH
Journal / Book Title
Small Science
Volume
5
Issue
12
Copyright Statement
© 2025 The Author(s). Small Science published by Wiley-VCH GmbH This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/41395522
PII: SMSC70155
Subjects
BROMINATION
CHARGE-TRANSFER
defects
EFFICIENCY
FABRICATION
HALIDE PEROVSKITE
Materials Science
Materials Science, Multidisciplinary
MECHANISM
Nanoscience & Nanotechnology
ORIGIN
OXIDATION
photochemistry
Science & Technology
Science & Technology - Other Topics
solar cells
STABILITY
SUBSTITUTION
Technology
tin perovskites
Publication Status
Published
Coverage Spatial
Germany
Article Number
e202500426
Date Publish Online
2025-11-11