Speaker: Dr Sudipta Seth, Postdoctoral Fellow, KU Leuven, Belgium.

Title: "Smart Multimodal Micro-Spectroscopy for Optoelectronic Materials and In-Operando Devices".

Date: Monday, 4th May 2026 - Time: 4 PM

Tea & Coffee: 5 PM

Venue: CeNSE Seminar Hall

Abstract:

The performance and stability of optoelectronic devices are conventionally evaluated through 
macroscopic photophysical and electrical measurements. However, these bulk properties are 
inherently shaped by complex nanoscopic structural, chemical, and functional heterogeneities. 
External stimuli such as light, electric bias, and environment can significantly influence 
local behaviour, making it essential to probe devices at the micro- and nanoscale under 
operating conditions. Conventional techniques, like scanning probe microscopy and 
electron/x-ray-based analytical methods, offer high spatial resolution but are 
primarily limited to structural characterisation and often alter operando conditions.


To address these challenges, I have developed Correlation Clustering Imaging (CLIM), a microscale 
functional imaging method that utilises photoluminescence fluctuations to reveal contrasts associated 
with defect dynamics in semiconductor materials. 1,2 CLIM images correlated with SEM reveal crucial 
information about the structure-function relationship in the bare thin films.  The local functional 
regions in a solar cell are more heterogeneous in size and shape than the film on glass. Moreover, 
the fluctuation amplitude and functional regions strongly depend on the device's operational regime. 
Statistical analysis of intensity fluctuations provides insights into the type of metastable defects 
responsible for fluctuating non-radiative recombination processes3 in thin films and operational solar 
cells.

Although this methodology enhances our understanding of device photo-physics, it is fundamentally 
limited to optical resolution and lacks the local energetic landscape of the devices. My future goal 
is to develop a super-resolution, multimodal correlative framework that integrates nanoscale spectroscopy 
and AI-driven analytics. This platform will enable in-depth, in-operando investigation of 
optoelectronic materials, paving the way for the rational design of efficient, durable next-generation devices.

References
1. B. Louis¥, S. Seth¥, Q. An, J. Ran, Y. Vaynzof, J. Hofkens, I. G. Scheblykin, Adv. Mater., 2025 37, 
   2413126.
2. T. Behera, B. Louis, L. Paesen, R. V. Brande, K. Asano, M. Vacha, M. Roeffaers, E. Debroye, 
   J. Hofkens*, S. Seth*. ChemRxiv 2025, https://doi.org/10.26434/chemrxiv-2025-5gbh4.
3. S. Seth, E. A. Podshivaylov, J. Li, M. Gerhard, A. Kiligaridis, P. A. Frantsuzov, I. G. Scheblykin, 
   Adv. Energy Mater. 2021, 11, 2102449.

Biography:

Sudipta Seth is currently a Marie Skłodowska-Curie Postdoctoral Fellow at KU Leuven, Belgium, 
where he conducts advanced research at the intersection of materials chemistry, optoelectronic devices, 
and spectroscopy, through the development of innovative microscopy methodologies. He completed his 
PhD at the University of Hyderabad and subsequently worked as a postdoctoral fellow at Lund 
University and as a visiting researcher at the Tokyo Institute of Technology and Max-Planck 
Institute for Polymer Research, Mainz. His work integrates single-particle spectroscopy, 
super-resolution and nanoscale microscopy, and ultrafast spectroscopy to investigate fundamental 
photo-physics in semiconductor materials and devices. He has received several academic fellowships, 
including INSPIRE-SHE (India), Wenner-Gren Postdoctoral Fellowship (Sweden), FWO Research stay 
abroad (Belgium), and Marie Sklodowska-Curie Postdoctoral Fellowship (European Commission).

Host Faculty:  Prof. Adithya Sadalana