Evaporation-Assisted Deposition of FAPbI3 and Interlayer for Solar Cells with Stability Exceeding 10,000 Hours

Cristian A. Villalobos Meza^a^,^b^,^c^,^d, Aslihan H. Babayigit^a^,^c^,^d, Sunil Suresh^a^,^c^,^d, Tamara Merckx^a^,^c^,^d, Tom Aernouts^a^,^c^,^d, Bart Vermang^a^,^c^,^d, Yinghuan Kuang^a^,^c^,^d, Jef Poortmans^a^,^b^,^c^,^d

^aImec, Imo-imomec, Thor Park 8320, 3600, Genk, Belgium

^bDepartment of Electrical Engineering (ESAT), KU Leuven, Kasteelpark Arenberg 10, Leuven, 3001, Belgium

^cHasselt University, Institute for Materials Research (IMO-IMOMEC), Martelarenlaan 42, 3500 Hasselt, Belgium

^dEnergyVille, imo-imomec, Thor Park 8320, 3600 Genk, Belgium

Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV26)

Uppsala, Sweden, 2026 May 18th - 20th

Organizers: Gerrit Boschloo, Ellen Moons, Feng Gao and Anders Hagfeldt

Oral, Cristian A. Villalobos Meza, presentation 142
Publication date: 11th March 2026

Hybrid vapor-solution processing offers a promising route to deposit perovskite absorbers on textured substrates, which is particularly attractive for tandem and multijunction photovoltaic applications. However, this approach has been predominantly applied to wide-bandgap compositions, while its potential for FAPbI₃-based perovskites remains underexplored. In this work, we investigate the deposition, passivation, and stability of vapor–solution-processed FAPbI₃ perovskite solar cells employing sputtered NiO_X hole-transport layers in a p–i–n architecture.

By systematically tuning the organic precursor composition and annealing conditions, we obtain uniform, large-grained perovskite films with minimal residual PbI₂. Building on this optimized baseline, we introduce a dual-interface passivation strategy using ultrathin CsBr layers deposited by thermal evaporation at both the buried NiO_X/perovskite interface and the perovskite top surface. Devices incorporating this CsBr treatment achieve power conversion efficiencies up to 23.25%, representing record performance for sputtered NiO_X-based p–i–n devices.

Beyond efficiency, the dual-interface passivation leads to exceptional thermal stability. Under ISOS-D-2I aging conditions (85 °C, dark, inert atmosphere), devices retain over 80% of their initial efficiency after more than 10,400 hours, significantly outperforming control devices. Morphological and optoelectronic analyses reveal suppressed formation of Pb-rich secondary phases, more homogeneous surface potentials, and improved preservation of carrier lifetimes upon aging.

Time-of-flight secondary ion mass spectrometry provides insight into the underlying stabilization mechanism, showing extensive redistribution of Cs and Br throughout the perovskite layer and a strong suppression of residual Cl. The presence of mobile Br appears to compensate halide loss during thermal stress, mitigating the formation of halide-deficient domains that lead to perovskite decomposition. Overall, this work demonstrates that scalable, vacuum-deposited interface engineering can simultaneously deliver high efficiency and exceptional thermal stability, highlighting a viable pathway toward durable perovskite photovoltaics compatible with industrial manufacturing.

Acknowledgements:

The authors want to acknowledge funding from the TRIUMPH Horizon Europe project, with grant agreement ID: 101075725

Funding was provided by Research Foundation − Flanders FWO, PhD Fellowship grant 1SE0225N.

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