Defect Passivation via a Bidentate Anchoring Molecule Enables Efficient and Stable Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy

Background:

• Perovskite solar cells (PSCs) face challenges with cation and anion defects at interfaces, limiting stability and efficiency.
• Undercoordinated Pb²⁺ and I⁻ defects are key culprits in perovskite degradation.

Purpose of the Study:

• To investigate the use of 4H-3-amino-1,2,4-triazole (4-HTAZ) as a dual-functional passivation agent for perovskite films.
• To improve the efficiency and long-term stability of perovskite solar cells by addressing interfacial defects.

Main Methods:

• Utilized 4-HTAZ molecule with dual-functional passivation groups (-NH₂, pyridinic-N, pyrrolic-N) for bidentate anchoring at perovskite surface defects.
• Characterized the impact of 4-HTAZ passivation on energy level alignment, charge extraction, and interfacial recombination.
• Assessed device stability under continuous light exposure and thermal stress.

Main Results:

• 4-HTAZ effectively passivated both cationic (Pb²⁺) and anionic (I⁻) defects.
• Optimized energy level alignment and promoted charge extraction, while inhibiting recombination.
• Achieved a champion power conversion efficiency (PCE) of 25.12%.
• Demonstrated enhanced stability, retaining 92.7% of initial efficiency after 500 hours of operation.

Conclusions:

• Bidentate passivation with 4-HTAZ significantly improves the performance and operational stability of perovskite solar cells.
• The inherent hydrophobicity of 4-HTAZ provides a protective barrier against environmental stressors.
• This passivation strategy offers a promising route for developing highly efficient and durable perovskite solar cells.