4-Bromobenzylamine Bidirectional Regulation Strategy Enables High-Efficiency and Stable Sn-Pb Perovskite Solar Cells.

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT/PSS) is a conductive polymer used in perovskite solar cells (PSCs).
• PEDOT/PSS can degrade due to moisture-induced acidity and rapid perovskite crystallization, impacting device performance.
• Inverted Sn-Pb PSCs face challenges with stability and efficiency due to these factors.

Purpose of the Study:

• To develop a bidirectional regulation strategy for efficient and stable inverted Sn-Pb PSCs.
• To investigate the role of 4-bromobenzylamine hydrochloride (4-BBAC) in improving PEDOT/PSS and perovskite film quality.
• To enhance the power conversion efficiency (PCE) and operational stability of Sn-Pb PSCs.

Main Methods:

• Incorporation of 4-bromobenzylamine hydrochloride (4-BBAC) molecules at the PEDOT/PSS/perovskite interface.
• Surface modification of PEDOT/PSS to improve conductivity and reduce acidity.
• Control over Sn-Pb perovskite crystallization kinetics and prevention of Sn2+ oxidation using 4-BBAC.
• Fabrication and characterization of optimized (HC(NH2)2)n(CH3NH3)1-nPb0.7Sn0.3IxBr3-x devices.

Main Results:

• 4-BBAC modified PEDOT/PSS, enhancing conductivity and reducing moisture-induced acidity.
• 4-BBAC facilitated the formation of a 2D perovskite phase, slowing crystallization and preventing Sn2+ oxidation.
• Optimized devices achieved a PCE of 18.36%, significantly higher than control devices (16.23%).
• Unencapsulated devices with 4-BBAC retained 71% of their initial PCE after 300 hours of humidity aging, compared to near-zero for control devices.

Conclusions:

• 4-BBAC serves as an effective interface modifier for improving the efficiency and stability of inverted Sn-Pb PSCs.
• The strategy addresses key degradation pathways, including PEDOT/PSS acidity and perovskite instability.
• This work provides a novel approach for fabricating high-performance and durable perovskite solar cells.