Modulating Adsorption Configurations of Hybrid Self-assembled Molecules Enables High-performance Inverted Perovskite...

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Self-assembled molecules (SAMs) are crucial as hole-selective layers in perovskite solar cells (PSCs).
• Controlling the adsorption configuration and orientation of hybrid SAMs on indium tin oxide (ITO) is vital for optimizing PSC performance but remains challenging.
• The homogeneity and orientation of SAMs significantly impact the interfacial properties and overall device efficiency.

Purpose of the Study:

• To investigate the modulation of [4-(3,6-diphenyl-9H-carbazol-9-yl)butyl]phosphonic acid (Ph-4PACz) SAM adsorption configuration on ITO using co-assembled molecules.
• To understand how different co-assembled molecules influence the orientation and homogeneity of Ph-4PACz films.
• To correlate interfacial improvements with enhanced photovoltaic performance and operational stability in PSCs.

Main Methods:

• Co-assembly of Ph-4PACz with 2,3,5,6-tetrafluoroterephthalic acid (BCA) or 2,3,5,6-tetrafluoro-4-sulfanylbenzoic acid (BSCA) on ITO substrates.
• Characterization of SAM adsorption configuration, orientation, and film homogeneity using surface analysis techniques.
• Fabrication and performance testing of perovskite solar cells incorporating the modified SAMs.

Main Results:

• Planar BCA molecules induced a tilted Ph-4PACz configuration (approx. 54.03°), while tilted BSCA molecules promoted an almost perpendicular orientation.
• BSCA co-assembly resulted in a more uniform Ph-4PACz film with improved energy level alignment and enhanced perovskite film homogeneity.
• BSCA-based devices achieved high power conversion efficiencies (26.72% for 0.0717 cm², 25.21% for 1 cm²) and excellent operational stability (>90% after 1500h illumination or 1000h at 85°C).

Conclusions:

• Co-assembly with BSCA effectively controls Ph-4PACz orientation on ITO, leading to superior interfacial properties in PSCs.
• The enhanced uniformity and energy level alignment at the SAM/ITO interface significantly reduce recombination losses and boost device performance.
• This strategy offers a promising pathway for developing highly efficient and stable perovskite solar cells.