Functional Group Engineering Stabilizing Precursor Solution and Passivating Defects for Operationally Stable and...

Area of Science:

• Materials Science
• Photovoltaics
• Chemical Engineering

Background:

• Perovskite solar cells (PSCs) suffer from performance degradation due to unstable precursor solutions.
• Deprotonation of organic cations and oxidation of iodide ions are key decomposition pathways.
• Engineering organic functional groups offers a route to enhance precursor stability.

Purpose of the Study:

• To investigate the impact of functional group position and type on perovskite precursor solution stability.
• To understand the role of acid dissociation constant (pK_a) in mitigating decomposition reactions.
• To optimize precursor formulation for high-performance and stable PSCs.

Main Methods:

• Synergistic engineering of organic functional groups on benzene rings.
• Correlation of functional group pK_a with precursor solution stability.
• Utilizing 4-hydrazinobenzenesulfonic acid (4-HBSA) for defect passivation.
• Fabrication of inverted PSCs using vacuum flash evaporation technology.

Main Results:

• Functional group position and type significantly influence pK_a and ink stability.
• Lowest pK_a achieved with 4-HBSA effectively suppresses decomposition reactions.
• Optimized PSCs demonstrate a certified power conversion efficiency (PCE) of 26.36%.
• The PSCs maintain 92% of their initial efficiency after 2000 hours of operation.

Conclusions:

• The pK_a of organic functional groups is critical for stabilizing perovskite precursor solutions.
• 4-HBSA is an optimal additive for enhancing PSC stability and efficiency.
• This work sets a new benchmark for PSCs fabricated under ambient conditions, showing high efficiency and long-term stability.