研究目的
To experimentally analyze a model lateral system, consisting of a vacuum deposited FAPbI3 layer and two symmetrical metal electrodes, in a pursuit of elucidating the subversive processes stimulated by the continuous current leakage in the dark, hereinafter termed as ECID (electrical current-induced degradation).
研究成果
The experiments demonstrate a fundamental instability of the gold/hybrid halide perovskite interface under constant current pressure in the dark. Gold species migrate into the perovskite matrix, leading to interface disruption and shrinkage of the interelectrode gap. This process can eventually cause short-circuiting or electrode exhaustion, highlighting intrinsic degradation mechanisms in perovskite photovoltaics that need addressing for improved device stability.
研究不足
The lateral geometry used is somewhat distant from a real solar cell scheme, which may limit direct applicability to vertical sandwich-type devices. The experiments were conducted in the dark without UV light, which differs from operational conditions under sunlight. The reliability of ToF-SIMS profiling in vertical structures is questioned due to potential atomic mixing from ion beam damage and interface roughening.
1：Experimental Design and Method Selection:
The study used a lateral geometry with vacuum-deposited FAPbI3 perovskite films and gold electrodes to investigate electrical current-induced degradation (ECID) in the dark. Methods included ToF-SIMS mapping, white-light interferometry (WLI), X-ray diffraction (XRD), and optical spectroscopy for comprehensive analysis of chemical, structural, and morphological changes.
2：Sample Selection and Data Sources:
FAPbI3 films (300 nm thick) were prepared on glass substrates via vacuum codeposition of PbI2 and FAI precursors. Gold strip electrodes were vacuum-deposited through a shadow mask with interelectrode gaps of 250 μm or 1 mm. Samples were subjected to ECID by applying external voltages (60 V for 250 μm gap, 300 V for 1 mm gap) for 8 hours in an inert atmosphere without illumination.
3：List of Experimental Equipment and Materials:
Equipment included TOF.SIMS V installation (IONTOF) with Cs and O sputtering guns, TalySurf CCI 2000 white-light interferometer (Taylor & Hobson), D8 Discover diffractometer (Bruker) with CuKα radiation, and FireFly4000 optical fiber spectrometer (CNI). Materials included PbI2, FAI, gold for electrodes, and glass substrates.
4：Experimental Procedures and Operational Workflow:
ECID was applied to samples, followed by ToF-SIMS imaging (500 × 500 μm raster sputtering, 330 × 330 μm analysis area) for lateral distribution of secondary ions (e.g., PbI3-, CH5N2+, Au+). WLI provided surface topography images, XRD analyzed crystal structure, and optical spectroscopy measured absorption in the interelectrode gap.
5：Data Analysis Methods:
ToF-SIMS data were reconstructed into 2D color-scaled maps for ion intensity. XRD patterns identified perovskite phases (α and δ polymorphs). Optical spectra were analyzed for absorption changes. Current density during ECID was estimated based on electrode dimensions.
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