Unravelling structure and growth mechanisms in beam-sensitive organic 2D crystals

 

Unravelling structure and growth mechanisms in beam-sensitive organic 2D crystals

 

Date: 13^th March, 2026 (Friday)

Time: 5 - 6 pm (HKT)

 

Venue: Lecture Theatre P2, Chong Yuet Ming Physics Building

 

 

Central Facility for Materials Science Electron Microscopy and Institute for Quantum Optics

Ulm University

 

Ute Kaiser received her Diploma and PhD in Crystallography and Physics from Humboldt University Berlin in 1976 and 1993, respectively. She completed her habilitation in Experimental Physics at the University of Jena, Germany, in 2002. From 2004 to 2023, she served as a Full Professor at Ulm University and headed the Materials Science Electron Microscopy Center in Ulm. Since October 2023, she has held the position of Senior Professor at Ulm University.

 

Between 2009 and 2018, she was the Scientific Director of the SALVE project, playing a key role in the development of low-voltage TEM technology. Her research focuses on applying this innovative technique to investigate and functionalize the properties of low-dimensional inorganic and organic materials. She has authored more than 400 papers in peer-reviewed journals (H index 93) and was Highly Cited Researcher (Materials Science) 2019. She is currently the Physical Sciences Editor for Micron.

 

Organic two-dimensional (2D) crystals unite tunable molecular design with exceptional electronic and mechanical properties, positioning them as promising building blocks for flexible electronics, sustainable energy devices and next-generation sensing technologies [1–4]. Because their macroscopic performance is dictated by atomic-scale order, precise structural characterization is essential to optimize functionality and unlock their full potential.

 

Although aberration-corrected transmission electron microscopy (TEM) can achieve sub-ångström resolution for inorganic 2D materials [3–5], atomic-precision imaging of organic 2D crystals remains elusive. Their intrinsic beam sensitivity, low atomic number contrast and dynamic structural behaviour under the electron beam demand imaging strategies that preserve integrity while resolving key structural motifs [6–8].

 

Here we investigate 2D organic crystals such as polyamine and -imine [7,8], metal–organic frameworks (MOFs) [10,11] and covalent organic frameworks (COFs) [12]. First we are focusing on defect imaging in polyimine and polyamine-based films with sub-2 nm resolution [7]. We show that employing an unusually low electron acceleration voltage of 120 kV—rather than the conventional 300 kV—is critical for achieving highest-resolution analysis [8]. We further identify design principles for MOFs with enhanced beam stability [9,10], leading to Cu₃(BHT) as the most stable architecture. In situ liquid-cell TEM reveals, however, that the growth process yields and unusal formation of Cu₄(BHT) instead [11], exhibiting different electronic properties.

 

[1] K. Liu et al., Nature Chemistry 11 (2019) 994,

[2] S. Fu, et al. Nature Materials (2025) doi.org/10.1038/s41563-025-02246-2

[3] A. Prasoon, et al. Advanced Materials (2025) 2505810

[4] T. Zhang, et al. Nature 638 (2025) 411

[3] M. Haider et al. Nature 392 (1998), 768

[4] M. Linck, et al. PRL 117 (2016) 076101

[5] Yi Jiang, et al. Nature 559, 2018, 343

[6] M. Kühne, F. Börrnert et al., Nature, 564 (2018) 234

[7] H. Qi et al., Science Advances 6, (2020) eabb5976,

[8] B. Liang et al. Nature Communication 13 (2022) 3948.

[9] D. Mücke, et al. Nano Letters 24 (2024) 3014

[10] D. Mücke et al., Micron 184 (2024) 103677

[11] D. Mücke et al. Crystal Growth & Design 25 (2025) 1622

[12] S. Ghouse, et al. Nature Chemistry (2026)