Constructing a Surface Multi-cationic Heterojunction for CsPbI_1.5Br_1.5 Perovskite Solar Cells with Efficiency beyond...

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• All-inorganic CsPbI1.5Br1.5 perovskite solar cells show promise for tandem applications due to thermal stability and performance.
• Current efficiencies are limited by non-radiative recombination and optical losses, hindering their potential.

Purpose of the Study:

• To develop an efficient and stable CsPbI1.5Br1.5 perovskite solar cell using a novel surface modification strategy.
• To address limitations in power conversion efficiency (PCE) and stability in inorganic perovskite solar cells.

Main Methods:

• Fabrication of CsPbI1.5Br1.5 perovskite films with controlled FA+ and MA+ content to form a surface multi-cationic heterojunction (SMH).
• Characterization of the heterojunction's impact on defect passivation, optical loss, energy-level alignment, and interfacial charge recombination.
• Performance testing of the resulting perovskite solar cell devices.

Main Results:

• The SMH effectively passivates surface defects and reduces optical losses in CsPbI1.5Br1.5 perovskite films.
• Improved energy-level alignment and reduced interfacial charge recombination were observed with the SMH.
• The champion device achieved a PCE of 14.11%, the highest reported for inorganic CsPbI1.5Br1.5 solar cells.
• The device retained 85% of its initial efficiency after 1000 hours of unencapsulated storage.

Conclusions:

• The surface multi-cationic heterojunction is a viable strategy for enhancing the efficiency and stability of inorganic perovskite solar cells.
• This method offers a pathway to overcome key limitations in perovskite photovoltaics, approaching theoretical performance limits.
• The developed solar cells demonstrate significant potential for future tandem solar cell applications.