Decoupling Bidirectional Photochemical Degradation via Radical Scavenging for Stable Inverted Perovskite Solar Cells

Area of Science:

• Materials Science
• Photovoltaics
• Chemical Engineering

Background:

• Interfacial instability between perovskite absorbers and fullerene electron transport layers hinders inverted perovskite solar cell (PSC) operational stability.
• A bidirectional coupling degradation mechanism involving photo-oxidation and PCBM acceleration has been identified.

Purpose of the Study:

• To elucidate the molecular origins of interfacial degradation in PSCs.
• To introduce a radical scavenger to disrupt the degradation cascade and enhance device stability.

Main Methods:

• Investigated a bidirectional coupling degradation mechanism at the perovskite/fullerene interface.
• Introduced 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy radical (O-TEMPO) as an interfacial radical scavenger.
• Evaluated device performance and stability under accelerated aging conditions.

Main Results:

• Discovered a self-reinforcing degradation cycle involving formamidinium iodide (FAI) photo-oxidation and PCBM dimerization.
• O-TEMPO effectively quenched iodine and carbon-centered radicals, suppressing degradation.
• O-TEMPO modified PSCs achieved 26.99% efficiency and retained 95.1% performance after 1000 hours.

Conclusions:

• Elucidated the molecular mechanisms of interfacial degradation in PSCs.
• Established radical-scavenging interfacial engineering as a universal strategy for enhancing PSC stability.
• Demonstrated a robust framework for developing highly stable perovskite photovoltaic technologies.