Minimizing Interfacial Defects at 3D/2D Perovskite Heterojunction for Efficient and Stable Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• 3D/2D perovskite heterojunction solar cells offer high power conversion efficiency (PCE) and stability.
• Transferring 2D perovskite crystals onto 3D perovskites promotes carrier transport but can create interfacial defects.
• Interfacial defects are a critical but often overlooked issue in these devices.

Purpose of the Study:

• To address interfacial defects in 3D/2D perovskite heterojunctions.
• To improve the performance and stability of 3D/2D perovskite solar cells.
• To investigate the role of an interfacial layer in defect mitigation and carrier transport.

Main Methods:

• Introduction of an octyl ammonium iodide (OAI) interfacial layer between 3D and 2D perovskite layers.
• Fabrication of 3D/OAI/2D heterojunction solar cells.
• Characterization of device performance, including PCE and stability under ambient storage and illumination stress.

Main Results:

• The OAI interlayer effectively passivates residual PbI2 and suppresses surface vacancy defects.
• The 3D/OAI/2D heterojunction exhibits improved lattice matching, inducing compressive strain.
• This leads to suppressed carrier recombination and enhanced carrier transport.
• Achieved a remarkable PCE of 25.07% with excellent long-term stability (retaining >90% PCE after 2500 h air storage or 1034 h illumination).

Conclusions:

• The OAI interlayer is a highly effective strategy for eliminating interfacial defects and lattice mismatch in 3D/2D perovskite heterojunctions.
• This approach significantly enhances both the efficiency and stability of perovskite solar cells.
• The developed 3D/OAI/2D heterojunctions show great promise for advanced optoelectronic applications.