Oxygen-Mediated (0D) Cs₄PbX₆ Formation during Open-Air Thermal Processing Improves Inorganic Perovskite Solar Cell...

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Chemistry

Background:

• Commercialization of perovskite solar cells requires scalable production methods.
• Open-air processing of perovskite films often leads to detrimental physical changes.
• The role of ambient oxygen in perovskite thin-film processing remains underexplored.

Purpose of the Study:

• To investigate the beneficial effects of ambient oxygen during open-air thermal processing of gamma-CsPbI3 perovskite films.
• To elucidate the mechanisms by which oxygen influences perovskite film structure and stability.
• To demonstrate the impact of oxygen-assisted processing on perovskite solar cell performance.

Main Methods:

• Utilized physiochemical-sensitive probes to study oxygen intercalation and bond formation.
• Analyzed the formation of a Cs4PbI6 capping layer during annealing above 330 °C.
• Fabricated and tested gamma-CsPbI2Br perovskite solar cells processed in dry air.

Main Results:

• Oxygen intercalation into CsPbI3 via iodine vacancies forms Pb-O bonds and superoxide (O2-).
• Annealing in air (>330 °C) drives the formation of a stabilizing Cs4PbI6 capping layer.
• This capping layer shields the perovskite from moisture and enhances lattice stability.
• Perovskite solar cells processed in dry air showed improved operational stability and photoconversion efficiency (12.7% to 15.4%).

Conclusions:

• Ambient oxygen plays a beneficial role in the thermal processing of metastable gamma-CsPbI3 perovskite films.
• The formation of a Cs4PbI6 capping layer via oxygen intercalation enhances device stability and performance.
• Open-air processing, leveraging ambient oxygen, offers a promising route for scalable perovskite solar cell fabrication, challenging the necessity of glovebox environments.