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HL: Fachverband Halbleiterphysik

HL 71: Quantum Dots and Wires: Optical Properties

HL 71.10: Talk

Thursday, March 10, 2016, 12:15–12:30, H15

Time-integrated and time-resolved luminescence studies of carbon nanodots — •Angelina Vogt¹, Kseniia Sergeeva¹, Frank Dissinger², Sebastian Resch², Siegfried Waldvogel², and Tobias Voss¹ — ¹Institute of Semiconductor Technology and LENA, TU Braunschweig — ²Institute of Organic Chemistry, Johannes Gutenberg University Mainz

Strongly luminescent and environmentally friendly carbon nanodots (C-dots) with diameters below 10 nm offer a great potential for optimized color conversion in LED displays and selective gas detection in sensing devices. Low toxicity, biocompatibility, excellent chemical and photo stability, inexpensive large-scale fabrication schemes and tunable photoluminescence (PL) emission are among their outstanding properties. Here, we study the luminescence properties of C-dots dissolved in distilled water for different concentrations of the C-dots, different excitation wavelengths and as a function of the laser power. The C-dots were hydrothermally synthesized and measured in the as-grown or a reduced state. In addition, we performed time-resolved studies of the luminescence dynamics with a femtosecond laser system to obtain a better understanding of the excitation and relaxation pathways of the photo-excited electrons, which is still controversially discussed in literature. The results show a luminescence decay time of several nanoseconds with a slightly faster decay on the high energy side of the PL emission. These results are analyzed with a model which takes into account electronic states of different sp2-hybridized carbon molecules which are believed to form the core of the C-dots.