Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 3: Molecular Electronics and Excited State Properties
CPP 3.7: Vortrag
Montag, 1. April 2019, 11:30–11:45, H13
Temperature Dependent Photoluminescence Studies on Zinc Phthalocyanine Single Crystals — •Larissa Lazarov1, Sebastian Hammer1, and Jens Pflaum1,2 — 1Experimental Physics VI, Julius Maximilian University of Würzburg, 97074 Würzburg — 2ZAE Bayern, 97074 Würzburg
Zinc-phthalocyanine (ZnPc) has been one of the most studied materials in organic solar cells, due to its high photostability, electronic tunability and superior opto-electronic properties compared with other metal-phthalocyanines [1]. Remarkably, the microscopic photophysical processes in ordered ZnPc aggregates have not been studied in great detail so far. For this purpose, we grew ZnPc single crystals via gradient sublimation and confirmed their crystallographic β-phase by X-ray diffraction. Temperature dependent photoluminescence (PL) studies have been performed from 4 to 330 K. Below 100 K the radiative 0-0 vibronic transition consists of two narrow lines with a FWHM of about 20 meV, respectively. The emission intensity in this temperature range indicates superradiance accompanied by exciton delocalization over several molecules according to Spano’s method [2]. Above 100 K, thermally activated aggregate emission appears to be the dominant process in PL enhancement by up to one order of magnitude at 330 K. We discuss the superradiant behavior in respect to its dependence on polarization and excitation power and shed light on the microscopic processes leading to the emission behavior at elevated temperatures.
[1] Brendel et al., Adv. Funct. Mater., 25, 2015
[2] Spano, F.C., Yamagata, H., JPCB 115, 5133-5143, 2011