Dual-Functionalized Bonding Management via Aromatic Formamidine Ligands Enables 25.57%-Efficient Ambient-Printed...

Area of Science:

• Materials Science
• Photovoltaics
• Chemical Engineering

Background:

• Ambient printing of perovskite solar cells (PSCs) is hindered by poor crystallization control under humid conditions, causing performance degradation.
• Existing ligand-assisted methods lack a deep understanding of how specific chemical bonds influence crystallization dynamics during ambient processing.

Purpose of the Study:

• To elucidate a dual-functionalized bonding (DFB) mechanism for controlling perovskite crystallization during ambient printing.
• To investigate how aromatic formamidine ligands with enhanced bifunctional binding impact crystallization dynamics and device performance.

Main Methods:

• Development and application of aromatic formamidine ligands with an electron-deficient triazole ring for dual coordination.
• Analysis of ligand coordination with [PbI6]4- octahedra and formamidinium ions (FA+) to understand nucleation and phase control.
• Fabrication and characterization of ambient-printed PSCs using the optimized ligands.

Main Results:

• The DFB mechanism effectively delays nucleation, suppresses detrimental δ-phase formation, and widens the recrystallization window.
• Optimized ligands lead to highly homogeneous perovskite films with reduced trap density and improved carrier diffusion.
• Ambient-printed PSCs achieved high power conversion efficiencies (up to 25.57% for small areas and 22.98% for mini-modules) and excellent operational stability (>90% retention after 1,000 hours).

Conclusions:

• The DFB mechanism provides a molecular-level strategy for achieving superior crystallization control in ambient-printed PSCs.
• This approach significantly enhances the efficiency and long-term stability of printed perovskite solar cells, paving the way for scalable manufacturing.