Stabilizing Halide Distribution in Mixed Halide Perovskites through Diammonium-Based Passivation.

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Mixed halide perovskite solar cells (PSCs) show promise for high-efficiency tandem photovoltaics.
• Performance is limited by light-induced halide segregation and defect-mediated recombination.

Purpose of the Study:

• To introduce 1,3-diaminopropane dihydroiodide (PDADI) as a surface passivator for wide bandgap perovskite films.
• To suppress halide migration and reduce defect densities in PSCs.

Main Methods:

• Surface passivation using PDADI on FA$_{0.83}$Cs$_{0.17}$Pb-(I$_{0.6}$Br$_{0.4}$)$_3$ films.
• Characterization using photoluminescence (PL), UV-vis spectroscopy, Fourier-transform infrared (FTIR) analysis, and space-charge-limited current (SCLC) measurements.
• Fabrication and testing of PSCs to evaluate performance metrics.

Main Results:

• PDADI significantly reduced light-induced phase segregation and PL peak shift.
• FTIR analysis confirmed PDADI's interaction with undercoordinated Pb$^{2+}$ and compensation of halide vacancies.
• PDADI passivation improved PSC power conversion efficiency from 14.11% to 16.54%, increased open-circuit voltage, and enhanced fill factor.
• Reduced J-V hysteresis from 9.6% to 3.6% indicated improved charge extraction and ion migration suppression.

Conclusions:

• PDADI effectively passivates wide bandgap mixed halide PSCs by suppressing halide migration and reducing defects.
• The dual interaction of PDADI stabilizes the perovskite lattice, enhancing device performance and stability.
• PDADI shows potential for advancing PSCs in tandem solar cell technologies.