In situ light-coupled TEM separates photochemical and radiolytic degradation in halide perovskites
Year: 2026
Type: preprint
Abstract: Metal halide perovskites degrade under the same illumination that powers them, yet nanoscale observation of this photochemistry is confounded by electron-beam damage in transmission electron microscopy (TEM). We introduce an optical-fiber-coupled closed-cell TEM platform with independent control over electron dose rate, illumination wavelength and power density, and gas environment, and use it to decouple photochemical from radiolytic degradation in CsPbBr3 in real time. After establishing beam-safe imaging conditions, we find that above-bandgap illumination induces preferential emergence of PbBr2 domains, the dominant detectable crystalline product, primarily at grain boundaries. In contrast, the electron beam alone reduces Pb2+ to metallic Pb0, a chemically and spatially distinct pathway. Sub-bandgap illumination produces no detectable spectroscopic change, supporting photocarrier generation rather than optical power deposition as a dominant driver. Decoupling light from the electron beam is a prerequisite for real-time imaging photochemistry in beam-sensitive materials.
Source: ChemRxiv
Language: English
Subfield: Structural Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7208708553