In situ light-coupled TEM separates photochemical and radiolytic degradation in halide perovskites
6 affiliations
- 1Department of Materials Science and Engineering
- 2Northwestern University
- 3Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center
- 4Department of Chemistry
- 5International Institute for Nanotechnology (IIN), Northwestern University
- 6Department of Chemical and Biological Engineering
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.
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BibTeX
@misc{saidov2026situ,
title = {{In situ light-coupled TEM separates photochemical and radiolytic degradation in halide perovskites}},
author = {Khakimjon Saidov and Pronoy Nandi and Zizhen Cai and Bin Chen and Edward H. Sargent and Mercouri G. Kanatzidis and Vinayak P. Dravid and Dayne F. Swearer},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008343/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008343/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - In situ light-coupled TEM separates photochemical and radiolytic degradation in halide perovskites
AU - Khakimjon Saidov
AU - Pronoy Nandi
AU - Zizhen Cai
AU - Bin Chen
AU - Edward H. Sargent
AU - Mercouri G. Kanatzidis
AU - Vinayak P. Dravid
AU - Dayne F. Swearer
PY - 2026
DA - 2026/09/04
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008343/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008343/v1
AB - 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.
ER -