Light-induced Degradation of MAPI Perovskite Thin Films Probed by AFM
Swarnendu Banerjee a, Mykhailo Khytko a, Lucie Landová a, Matěj Hývl a, Antonín Fejfar a, Martin Ledinský a
a Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 16200, Prague 6, Czech Republic.
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV25)
Roma, Italy, 2025 May 12th - 14th
Organizers: Filippo De Angelis, Francesca Brunetti and Claudia Barolo
Poster, Swarnendu Banerjee, 259
Publication date: 17th February 2025

Perovskite thin films show excellent optoelectronic properties for next-generation solar cells. However, their long-term stability under operating conditions remains a critical challenge. We investigate the degradation mechanisms of Methylammonium Lead Iodide (MAPI) perovskite thin films, using AFM in controlled nitrogen atmospheres. Based on prior research on light-induced degradation in ambient conditions,1,2 this study isolates the role of light under controlled nitrogen environments.

We aimed to assess the degree to which the degradation caused by light alone differs in nitrogen compared to ambient conditions. Surface morphology, roughness, and any potential variations were compared across both conditions. MAPI thin films exposed to a controlled nitrogen environment exhibited negligible morphological changes under AFM analysis, both in darkness or under low light intensity. This is due to the absence of moisture and oxygen in the nitrogen environment, which contributes additionally to degradation. Thus, this approach facilitates the isolation of light-induced degradation from moisture and oxygen.

We observed a light intensity threshold, and a minimum exposure time required to initiate perovskite film degradation within a nitrogen environment. This suggests even in inert atmospheres, photochemical pathways remain active, albeit potentially slowed. To isolate the effects of light and other environmental factors, we quantify the degradation in ambient darkness and under illumination in nitrogen, exceeding the established threshold light intensity and time. This highlights the independent or synergistic contributions of light and other factors to perovskite film degradation, further validating nitrogen's protective role in enhancing solar cell longevity.

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