Controlled Grain Growth Deposition for Enhanced Bulk and Interfacial Defect Passivation in Vacuum-Deposited FAPbI₃...

Area of Science:

• Materials Science
• Solid-State Physics
• Photovoltaics

Background:

• Vacuum deposition of perovskite thin films offers advantages over solution-based methods but suffers from non-uniform nucleation and island-like growth.
• This leads to defects like columnar grains, voids, and trap states at the electron-transport layer (ETL)/perovskite interface, increasing non-radiative recombination.

Purpose of the Study:

• To develop a novel deposition method for high-quality perovskite thin films with improved structural properties and reduced interfacial defects.
• To enhance the performance of perovskite solar cells by addressing issues in vacuum deposition processes.

Main Methods:

• A controlled grain growth deposition (CGGD) method was developed using formamidinium lead iodide (FAPbI3) components.
• An ultrathin 3.5 nm lead iodide (PbI2) layer was pre-deposited on atomic layer deposited SnO2 as a nucleation template, followed by FAI/PbI2 co-evaporation.

Main Results:

• The CGGD method enabled uniform nucleation and laterally coherent grain growth, suppressing island-like FAI growth and yielding 18.6% larger grains.
• A 34% reduction in trap-state density and nearly twofold longer carrier lifetimes were observed in the resulting FAPbI3 films.
• Perovskite solar cells fabricated using CGGD achieved a stabilized power conversion efficiency (PCE) of 19.9%.

Conclusions:

• The CGGD method provides a pathway to high-quality vacuum-deposited perovskite films by improving crystallization and interfacial defect passivation.
• This approach facilitates the development of scalable optoelectronic devices with enhanced performance.
• The study demonstrates the effectiveness of nucleation control in overcoming limitations of conventional vacuum deposition techniques.