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Published on: February 3, 2021
Non-Phosphonic Self-Assembled Molecules with Weak Acidity for Inverted Perovskite Solar Cells
Bo Feng1, Wen Li1, Zhengbo Cui1
1School of Physics, Engineering Research Center of Nanophotonics & Advanced Instrument, Ministry of Education, East China Normal University, Shanghai, China.
Small (Weinheim an Der Bergstrasse, Germany)
|August 4, 2026
Summary
Researchers developed a new molecule, 9-carbazoleacetic acid (9AACz), to improve inverted perovskite solar cells (PSCs). This molecule reduces acidity, preventing perovskite degradation and enhancing device efficiency and stability.
Area of Science:
- Materials Science
- Renewable Energy
- Nanotechnology
Background:
- Self-assembled monolayers (SAMs) are crucial for advancing inverted perovskite solar cells (PSCs).
- The phosphonic acid group in conventional SAMs causes acidity, accelerating perovskite degradation and limiting device lifespan.
- Developing stable and efficient PSCs requires addressing the issue of acid-induced degradation.
Purpose of the Study:
- To design and synthesize a novel SAM molecule with reduced acidity for inverted PSCs.
- To investigate the effect of a carboxylic acid-based SAM on perovskite stability and device performance.
- To enhance the operational stability and power conversion efficiency of inverted PSCs.
Main Methods:
- Synthesized 9-carbazoleacetic acid (9AACz), a SAM molecule featuring a carboxylic acid group instead of a phosphonic acid group.
- Fabricated inverted PSCs using 9AACz on ITO substrates, leveraging the interaction between carboxylic and hydroxyl groups.
- Evaluated device performance through efficiency measurements and stability testing under thermal stress (85°C for 700 h).
Main Results:
- The new 9AACz SAM effectively self-assembles on ITO, improving work function regulation and hole extraction.
- The reduced acidity of 9AACz significantly inhibits acid-induced perovskite degradation, enhancing device stability.
- The fabricated inverted PSCs achieved a high power conversion efficiency of 26.1% and retained approximately 90% of their initial efficiency after 700 hours of stability testing.
Conclusions:
- Replacing phosphonic acid with carboxylic acid in SAMs offers a viable strategy to mitigate perovskite degradation in PSCs.
- The 9AACz SAM demonstrates excellent potential for fabricating highly efficient and stable inverted perovskite solar cells.
- This work provides a pathway for developing more durable perovskite solar cell technologies.
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