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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 9: Nanoparticles and Composite Materials II (joint session CPP, BP)

CPP 9.11: Talk

Monday, March 16, 2015, 17:45–18:00, C 243

Semiconductor Nanocrystal Blinking monitored via Fast Spectrally and Intensity Resolved Single Molecule Spectroscopy — •Clemens Göhler, Cornelius Krasselt, and Christian von Borczyskowski — Fakultät für Naturwissenschaften, TU Chemnitz, D-09126 Chemnitz

Colloidal CdSe Semiconductor Nanocrystals (NCs) are promising candidates for improving different applications, e.g. in photovoltaics or sensoring, due to their size-dependend optical and spectroscopic properties. With techniques from Single Molecule Spectroscopy, we avoid ensemble-averaging and investigate these characteristics on individual NCs. On that level, luminscence intermittency (so called blinking) is observable, for which the underlying mechanisms are yet not fully understood.

To contribute, we applied Change-Point-Analysis to time-correlated single-photon counts from single NC photoluminescence (PL) emission, which allows resolving discrete PL intensity levels [1]. In addition, we splitted the PL-signal with a dichroic beamsplitter towards two detectors. By combining these techniques, we were able to examine spectral diffusion within the single NC PL on a µs-timescale and to correlate that to the fluctuating emission intensity. The results are in agreement with blinking models based on a multiple recombination-center approach.

 [1] Schmidt, R., Krasselt, C., Göhler, C., & von Borczyskowski, C. (2014). ACS nano, 8(4), 3506-3521.