Spontaneous Heterointerface Modulation by a Methylammonium Tetrafluoroborate Additive for a Narrow-Bandgap FAPbI₃...

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite solar cells (PSCs) show improved performance with perovskite photoabsorbers.
• Formamidinium-lead-iodide (FAPbI3) is a narrow-bandgap absorber crucial for n-i-p PSCs.
• Modulating FAPbI3 properties while maintaining its narrow bandgap is key for PSC advancement.

Purpose of the Study:

• To investigate methylammonium tetrafluoroborate (MABF4) as an additive for narrow-bandgap FAPbI3 photoabsorbers.
• To enhance photovoltaic (PV) performance in PSCs by addressing interface properties.
• To understand the mechanism of MABF4's effect on FAPbI3 heterointerfaces.

Main Methods:

• Utilized methylammonium tetrafluoroborate (MABF4) as an additive in FAPbI3 photoabsorbers.
• Analyzed the modulation of heterointerfaces between FAPbI3 and carrier-transport materials (hole-transport and TiO2 electron-transport).
• Employed time-resolved microwave conductivity measurements to assess carrier traps and mobility ratios.

Main Results:

• MABF4 addition improved PV performance primarily by modulating heterointerfaces, not bulk FAPbI3 quality.
• MABF4 effectively eliminated surface defects at the hole-transport material/FAPbI3 interface.
• BF4-derived species segregated at the FAPbI3/TiO2 interface, modulating it and eliminating carrier traps.

Conclusions:

• MABF4 is a viable additive for narrow-bandgap FAPbI3 photoabsorbers in PSCs.
• The additive functions by suppressing defects and carrier traps at heterointerfaces.
• Findings offer a new strategy for developing advanced FAPbI3-based PSCs.