Mitigating Filamentary Conduction with SiN_xO_y to Enhance Reverse-Bias Stability in Inverted Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite solar cells (PSCs) have seen significant progress in operational stability against environmental factors.
• However, the stability of PSCs under reverse bias conditions, particularly those using NiO_x/SAM hole-selective contacts, is not well understood.
• Reverse bias can lead to device degradation, limiting the long-term reliability of PSCs.

Purpose of the Study:

• To investigate and address the largely unexplored issue of reverse bias stability in NiO_x/SAM-based perovskite solar cells.
• To develop a strategy for mitigating degradation caused by reverse bias stress.
• To evaluate the impact of a novel modification on both device efficiency and stability.

Main Methods:

• Modification of the self-assembled monolayer (SAM) with perhydropolysilazane (PHPS).
• Fabrication of PSCs incorporating the PHPS-modified SAM.
• Testing device performance and stability under reverse bias conditions (-1.2 V) for extended periods (380 h).

Main Results:

• The PHPS modification effectively suppressed silver (Ag) filament formation, a key degradation pathway under reverse bias.
• PHPS-modified PSCs exhibited significantly improved stability under reverse bias, retaining approximately 84% of their initial efficiency after 380 h.
• Control devices without PHPS modification degraded to about 60% of their initial efficiency under identical conditions.
• A slight enhancement in power conversion efficiency was also observed with the PHPS modification.

Conclusions:

• Reverse bias instability is a critical reliability challenge for NiO_x/SAM-based perovskite solar cells.
• Perhydropolysilazane (PHPS) modification of the SAM is a highly effective strategy to enhance reverse bias stability.
• This approach offers a promising pathway for improving the long-term operational reliability of perovskite solar cells.