Berlin 2018 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 52: Optical properties & Photonic crystals
HL 52.2: Vortrag
Freitag, 16. März 2018, 09:45–10:00, EW 201
Rydberg-like states in organic semiconductor rods — •Aswin Asaithambi1, Daichi Okada2, Guenther Prinz1, Yohei Yamamoto2, and Axel Lorke1 — 1Lotharstrasse 1, Faculty of Physics, CENIDE, University of Duisburg-Essen, Duisburg 47057, Germany — 2Division of Material Science, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Japan
Organic semiconductor Borondipyrromethene (BODIPY) derived samples have drawn much attention in recent years in the field of bio-imaging due to their good photo-physical properties such as high extinction coefficient and quantum yield. BODIPY molecules, under certain conditions, can be grown into rods. Different growth methods result in BODIPY rods with different photo-emission wavelengths.
In this contribution we show photo-luminescence (PL) spectra from different rods under 405nm laser excitation. Emitted light from the rods can travel through the rod due to total internal reflection, combining their excellent PL properties with waveguide physics. The light intensity emitted at the end of the rod shows an exponential decrease as the distance between end of the rod and the excitation spot is increased. This is attributed to reabsorption and scattering. We quantify the extinction parameter for different rods and compare them. Interestingly, the PL spectrum from the green emitting rod, shows, besides a broad luminescence, a set of peaks with energies that follows a 1/n2 rule. Such behavior, known from Rydberg atoms comes unexpected. The spectra will be discussed using different models such as Rydberg excitons or charge accumulation in the crystal.