Dresden 2017 – scientific programme

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O: Fachverband Oberflächenphysik

O 45: Organic-Inorganic Hybrid Systems and Organic Films

O 45.24: Poster

Tuesday, March 21, 2017, 18:30–20:30, P1A

Spectroscopy from 1,3-Diphenylisobenzofuran films on Cu(111) and Au(100) — •Janek Rieger, Angelika Demling, David Nobis, Daniel Niesner, Feifei Xiang, M. Alexander Schneider, and Thomas Fauster — Lehrstuhl für Festkörperphysik, FAU Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen, Germany

Thin films of 1,3-Diphenylisobenzofuran (DPIBF) show singlet fission, a mechanism for multi-exciton generation that might be used to enhance the efficiency of organic photovoltaics [1]. The yield of singlet fission depends strongly on the structural polymorph of the film [2]. Mixtures of several polymorphs were shown to form on oxide substrates. We use optical and photoelectron spectroscopies, scanning tunneling microscopy and thermal desorption spectroscopy to investigate DPIBF deposited on Cu(111) and Au(100) by thermal evaporation. Results are presented for various growth temperatures and for film thicknesses from one monolayer to 40 nm. While growth on Au(100) results in coexisting structures at all tested conditions, phase-pure films are prepared on Cu(111). The first layer adsorbs in an ordered structure at room temperature, with a molecular arrangement similar to the one in crystals. For thicker films, single series of photoluminescence peaks are found. The singlet transition blueshifts with increasing preparation temperature for DPIBF on both substrates. The maximum singlet energy is close to 2.8 eV, sufficient to support singlet fission [2].

[1] J. C. Johnson et al., J. Am. Chem. Soc. 132 (2010) 16302

[2] J. L. Ryerson et al., J. Phys. Chem. C 118 (2014) 12121