Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 51: Organic-Inorganic Systems II: Energy Level Alignment

O 51.7: Vortrag

Mittwoch, 9. März 2016, 12:15–12:30, S054

Photoemission study of thin films of the singlet fission compound 1,3-Diphenylisobenzofuran — •David Nobis, Janek Rieger, Daniel Niesner, Pedro B. Coto, Michael Thoss, and Thomas Fauster — Universität Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen, Germany

Singlet fission (SF) is the conversion of an optically excited, high-energy singlet exciton, into two optically dark, long-lived electronic excited triplet states via a spin-allowed process. This process might be used in next generation solar cells to harvest high-energy light. 1,3-Diphenylisobenzofuran (DPIBF) is a prototypical SF molecule, as has been shown by calculations and optical spectroscopy [1,2].
We investigated thin films of DPIBF on SiO₂ with UV photoelectron spectroscopy (UPS) and two-photon photoemission (2PPE). The UPS results show the HOMO located 6 eV below the vacuum level, in good agreement with DFT calculations.
The 2PPE spectra show the first singlet state S₁ at 2.8 eV above the HOMO. The triplet state is 1.4 eV lower in energy. Its high, long-lived population is explained by SF in agreement with literature [2].

[1] Schwerin A. F. et al., J. Phys. Chem. A 114 (2010) 1457

[2] Johnson J. C. et al., Phys. Rev. B 132 (2009) 16302