Dresden 2026 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 15: Organic Semiconductors: Optics and Photonics
HL 15.1: Vortrag
Dienstag, 10. März 2026, 09:30–09:45, POT/0006
Accessing 'Slow' Dynamics in Photocatalysts with PIAS — •Maria Ferree1, Rebecca Gröninger2, Tianhao Xue1, Thomas Bein1, Bettina Lotsch2, and Frédéric Laquai1 — 1Dept. Physical Chemistry, LMU München, Germany — 2Max Planck Institute for Solid State Research, Stuttgart, Germany
Quasi-steady-state Photoinduced Absorption Spectroscopy (PIAS) is a highly sensitive tool for probing long-lived excited states and charge carriers in semiconductors. We showcase PIAS capabilities by studying diverse systems, ranging from conjugated polymers and COF-based films to nanoparticle dispersions. PIAS is often overshadowed as researchers default to sophisticated Transient Absorption (TA) Spectroscopy. However, low-frequency modulated excitation with lock-in signal detection capture extremely weak changes in transmission induced by polarons or triplet states with lifetimes ranging from nanoseconds to seconds - dynamics that remain largely inaccessible by TA, but highly relevant for diffusion-limited processes, e.g. photocatalysis. Frequency-dependent measurements provide insight into lifetimes and concentrations of long-lived species. Whilst Time-resolved Photoluminescence (TRPL) can further reinforce the conclusions obtained from PIAS by extracting exciton recombination kinetics. Our studies of organic semiconductor-based photocatalysts are a reminder that PIAS is a powerful, often more suitable method complementary to ultrafast spectroscopy and other characterisation techniques. It provides unique access to 'slow' excited-state dynamics through relatively straightforward data acquisition and processing.
Keywords: Photoinduced absorption; Photocatalysis; Organic semiconductors; CO2 reduction; Time-resolved photoluminescence