Primary Photoexcitations and the Origin of the Photocurrent in Rubrene Single Crystals

Hikmat Najafov, Ivan Biaggio, Vitaly Podzorov, Matthew F. Calhoun, and Michael E. Gershenson
Phys. Rev. Lett. 96, 056604 – Published 9 February 2006

Abstract

By simultaneously measuring the excitation spectra of transient luminescence and transient photoconductivity after picosecond pulsed excitation in rubrene single crystals, we show that free excitons are photoexcited starting at photon energies above 2.0 eV. We observe a competition between photoexcitation of free excitons and photoexcitation into vibronic states that subsequently decays into free carriers, while molecular excitons are instead formed predominantly through the free exciton. At photon energies below 2.25 eV, free charge carriers are created only through a long-lived intermediate state with a lifetime of up to 0.1 ms and no free carriers appear during the exciton lifetime.

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  • Received 27 October 2005

DOI:https://doi.org/10.1103/PhysRevLett.96.056604

©2006 American Physical Society

Authors & Affiliations

Hikmat Najafov and Ivan Biaggio

  • Department of Physics and Center for Optical Technologies, Lehigh University, Bethlehem, Pennsylvania 18015, USA

Vitaly Podzorov, Matthew F. Calhoun, and Michael E. Gershenson

  • Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA

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Issue

Vol. 96, Iss. 5 — 10 February 2006

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