Dresden 2026 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 23: Transport Properties
HL 23.4: Talk
Wednesday, March 11, 2026, 10:15–10:30, POT/0051
Elucidating mobile charge carriers in granular matter by transient surface photovoltage analysis — •Christoph Merschjann1, Albert These2, Christoph Brabec2,3, Thomas Dittrich1, and Pablo Jimenéz-Calvo2,4 — 1Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin — 2Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen — 3Helmholtz-Institute Erlangen-Nürnberg, Erlangen — 4Max-Planck-Institute of Colloids and Interfaces, Potsdam
Among the most important properties of novel functional materials are their charge transport characteristics, including n vs. p type conductivity, carrier concentrations, and respective mobilities. However, new solid-state materials are typically first synthesized in granular form, and often this is also the intended morphology for applications (batteries, photocatalysts, etc.). This makes most electrical characterization techniques (e.g. impedance, Hall, time-of-flight photocurrent) extremely challenging, as they rely on current measurements throughout the bulk of the sample. To overcome this drawback, we use contact-less transient surface photovoltage (TR-SPV) to detect charge-density shifts on the nanometer scale and in a time range from nanoseconds to seconds. Comparing the results with diffusive charge-transport models of moderate complexity, we are able to deduce the type and mobility of photoinduced charge carriers in a prominent example material, graphitic polymeric carbon nitride (PCN). We encourage transferability of this SPV analysis to other 2D layered systems like metal- or covalent-organic frameworks (MOF / COF).
Keywords: charge transport; surface photovoltage; granular materials; covalent organic frameworks; quantitative spectroscopy