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Updated: Apr 5, 2026
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Influence of Hybrid Perovskite Fabrication Methods on Film Formation, Electronic Structure, and Solar Cell Performance
Published on: February 27, 2017
19.2K
Tracing the Dynamic Chemical Transformations of Spiro-OMeTAD in Operating Perovskite Solar Cells
Chittaranjan Das1,2, Mayank Kedia1,2, Kenedy Tabah Tanko3
1Institute for Photovoltaics (Ipv), Research Center SCoPE and Integrated Quantum Science and Technology Center (IQST), University of Stuttgart, Stuttgart, Germany.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|April 4, 2026
Summary
The widely used Spiro hole transport layer in perovskite solar cells degrades due to LiTFSI breakdown under operational stress. This instability, particularly under maximum power point tracking, reduces solar cell efficiency and highlights the need for more stable dopants.
Area of Science:
- Materials Science
- Renewable Energy
- Photovoltaics
Background:
- Perovskite solar cells (PSCs) face stability issues, particularly with the Spiro-OMeTAD (Spiro) hole transport layer (HTL) doped with LiTFSI in n-i-p devices.
- Understanding degradation mechanisms is crucial for improving PSC durability.
Purpose of the Study:
- To systematically investigate the causes of instability in n-i-p PSCs using the Spiro HTL under various stress conditions.
- To elucidate the chemical and interfacial changes within the HTL during degradation.
Main Methods:
- Utilized sputtering depth profile X-ray photoelectron spectroscopy (SDP-XPS) to analyze HTL composition and chemical states.
- Examined PSCs under shelf-life stability (SLS), open-circuit potential (OCP), and maximum power point tracking (MPPT) conditions.
Main Results:
- Discovered LiTFSI breakdown under operational stress, leading to Spiro degradation and altered p-type properties.
- Identified LiF and LiXSYOZ as byproducts of LiTFSI dissociation, initiating Spiro degradation, especially under MPPT and OCP.
- Observed a decrease in band bending from 0.6 eV (SLS) to 0.4 eV (MPPT/OCP), correlating with reduced open-circuit voltage and fill factor.
Conclusions:
- Operational stress, particularly MPPT and OCP, accelerates Spiro HTL degradation via LiTFSI breakdown.
- The formation of LiF and LiXSYOZ byproducts significantly impacts PSC performance.
- Enhanced dopant stability and novel HTL designs are essential for improving the long-term durability of perovskite solar cells.
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