Direct observation of Fröhlich polaron formation in BiOI nanoplatelets

Physical Review Materials 2026

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Authors: Matthias F. Kestler, Kyung Chul Woo, Junyeob Lim, Lucas M. Prins, Jochen Feldmann, Zhi-Heng Loh
DOI: 10.1103/wcq2-gpmz
Cited by: 2
References: 44

Abstract

For large polarons, Fröhlich theoretically derived an increased effective mass and a decreased energy as compared to free charge carriers. These changes have hitherto eluded direct observation. Here, we report on the direct observation of large polaron formation after photoexcitation in BiOI nanoplatelets, a system known to host spatially separated e-h pairs. We employ time- and momentum-resolved photoemission electron microscopy with 50-fs pulses to monitor the dynamics of the conduction-band (CB) dispersion 𝐸⁡(𝑘). Indeed, we observe a doubling of the effective mass accompanied by a decrease of the CB energy leading to an overall drop of 160 meV.

Fields of Study & Subjects

Advanced Thermoelectric Materials and Devices Copper-based nanomaterials and applications ZnO doping and properties

Publication details

Journal / source
Physical Review Materials
Publisher
American Physical Society (APS)
Volume
10
Issue
2
Publication date
2 January 2026
Language
EN