Chelating Coordination Regulates Perovskite Crystallization and Defect Passivation in Sn-Pb Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Chemistry

Background:

• Tin-lead perovskites (TLP) are promising narrow-bandgap absorbers for photovoltaics.
• Challenges include uncontrolled crystallization, Sn²⁺ oxidation, and interfacial defects limiting TLP device efficiency and stability.

Purpose of the Study:

• To develop a chelating coordination strategy using ethylenediamine diacetate (EDDA) to improve TLP crystallization and defect passivation.
• To investigate EDDA's effect on the buried and top perovskite interfaces for enhanced photovoltaic performance.

Main Methods:

• Post-treatment of PEDOT:PSS with EDDA to mitigate surface acidity and reduce insulating domains.
• Utilizing EDDA's carboxylate and amine groups to coordinate with cations and form hydrogen bonds within TLP.
• Employing EDDA for chemical polishing of the TLP top surface to inhibit oxidation and reduce defects.

Main Results:

• EDDA treatment promotes homogeneous, orderly (100)-facet crystal growth in TLP films.
• Enhanced charge extraction and reduced Sn²⁺ oxidation observed.
• Achieved a power conversion efficiency (PCE) of 23.30% with an open-circuit voltage of 0.877 V and fill factor of 81.81%.

Conclusions:

• EDDA effectively regulates TLP crystallization and passivates defects at both buried and top interfaces.
• The strategy significantly enhances the efficiency and stability of tin-lead perovskite solar cells.
• The developed TLP devices exhibit excellent performance and improved operational and storage stability.