Holger Röhm | Searcharxiv

arXiv2026

Ferroelectric domains in methylammonium lead iodide perovskite thin-films

We explore the ferroic properties of methylammonium lead iodide perovskite solar cells by Piezoresponse Force Microscopy (PFM). In vertical and horizontal PFM imaging, we find domains of alternating polarization with a width of 90 nm which we identify as polarized ferroelectric domains. High-resolution photo-conductive atomic force micrographs under illumination also show alternating charge carrier extraction patterns which we attribute to the local vertical polarization components within the ferroelectric domains. The correlation of the sample properties with Atomic Force and Kelvin Probe Force Micrographs evidence the piezo-electric nature of the domains.

cond-mat.mtrl-sci↗

arXiv2025

A self-driving lab for solution-processed electrochromic thin films

Solution-processed electrochromic materials offer high potential for energy-efficient smart windows and displays. Their performance varies with material choice and processing conditions. Electrochromic thin film electrodes require a smooth, defect-free coating for optimal contrast between bleached and colored states. The complexity of optimizing the spin-coated electrochromic thin layer poses challenges for rapid development. This study demonstrates the use of self-driving laboratories to accelerate the development of electrochromic coatings by coupling automation with machine learning. Our system combines automated data acquisition, image processing, spectral analysis, and Bayesian optimization to explore processing parameters efficiently. This approach not only increases throughput but also enables a pointed search for optimal processing parameters. The approach can be applied to various solution-processed materials, highlighting the potential of self-driving labs in enhancing materials discovery and process optimization.

cs.LG↗