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O: Fachverband Oberflächenphysik

O 104: Focus Session: Ultrafast Processes in Organic Semiconductors and Perovskites III (joint session O/CPP)

O 104.5: Talk

Friday, March 22, 2024, 11:30–11:45, MA 004

Ultrafast dynamics in polymeric carbon nitride thin films probed by time-resolved extreme-ultraviolet photoemission spectroscopy — Nataliia Kuzkova^1,2, Igor Yu. Kiyan¹, Iain Wilkinson¹, and •Christoph Merschjann¹ — ¹Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany — ²Advanced Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands

Polymeric carbon nitrides (PCN) have been extensively studied for various possible applications, mainly in the field of photocatalysis, but also as potential organic semiconductors, luminescent materials, etc. Especially photocatalytic applications are affected by the apparently low charge-separation and transport efficiency of PCN. It is therefore of interest to investigate the early-time dynamics of photoexcited charge carriers, specifically at the surface of the photocatalyst. To this end, we applied femtosecond time-resolved pump-probe extreme-ultraviolet photoemission spectroscopy (TRPES) to differently synthesized PCN thin films. Excitation at 400 nm sequentially populates a pair of short-lived transient species, which subsequently produce two different long-lived excited states on a sub-picosecond time scale. These could be assigned to singlet-exciton and charge-transfer states with a high initial spatial correlation, respectively. The results also show the potential of TRPES as a tool for in-situ investigations of early-time dynamics in photocatalytic processes.

[1] Kuzkova et al., Phys. Chem. Chem. Phys., 25, 27094 (2023)