Bifunctional Ligand Anchoring Modulates Colloidal Nucleation and Intermediate-Phase Crystallization for...

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Chemistry

Background:

• α-formamidinium lead triiodide (α-FAPbI₃) perovskites are promising for photovoltaics due to their narrow bandgap and thermal stability.
• Solution-processed films often contain inactive δ-FAPbI₃, hindering device performance.
• Controlling crystallization is key to achieving high-quality perovskite films.

Purpose of the Study:

• To improve the phase purity and film morphology of α-FAPbI₃ perovskite films.
• To enhance the performance and stability of perovskite solar cells.
• To investigate the role of 3-(pentafluorophenyl)propionic acid (PFPA) in perovskite film formation.

Main Methods:

• Modulation of perovskite precursor solutions with 3-(pentafluorophenyl)propionic acid (PFPA).
• Fabrication of perovskite solar cells using modified precursor solutions.
• Characterization of film morphology, phase purity, and device performance (PCE, hysteresis).
• Long-term stability testing under continuous illumination and damp-heat conditions.

Main Results:

• PFPA addition promoted uniform colloid formation and controlled solvent evaporation.
• Reduced nucleation barriers led to the growth of perovskite nanocrystals, resulting in dense, pinhole-free films.
• Improved phase purity was achieved, suppressing amorphous or mixed phases.
• Power conversion efficiencies (PCE) of 26.41% (0.09 cm²) and 24.38% (1 cm²) were obtained with negligible hysteresis.
• Devices retained >90% initial efficiency after 1500 h of continuous operation and >85% after 1300 h under damp-heat conditions.

Conclusions:

• PFPA is an effective additive for improving the quality and stability of α-FAPbI₃ perovskite films.
• The developed method enables the fabrication of high-performance, stable perovskite solar cells.
• This approach offers a pathway towards commercially viable perovskite photovoltaic technology.