Photogenerated geminate charge-pair separation mechanisms in pentacene crystals

• Published in: Chemical physics Vol. 94; no. 1; pp. 77 - 90
• Main Authors: Silinsh, E.A., Jurgis, A.J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.01.1985; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic transport in condensed matter; Exact sciences and technology; Photoconduction and photovoltaic effects; photodielectric effects; Physics; Polaron; Temperature; Computer simulation; Theoretical study; Threshold energy; Condensed benzenic compound; Small polaron; Electric field; Photoionization; Frequency; Effective mass; Photoconductivity; Organic compounds
• ISSN: 0301-0104
• DOI: 10.1016/0301-0104(85)85067-9

Results of computer-simulated studies of charge-pair separation mechanisms in pentacene (Pc) crystals are presented. Both charge-separation stages — thermalization and charge-pair dissociation — are simulated in a framework of an extended Sano-Mozumder model. Mean separation distance and geminate charge-pair dissociation efficiency have been calculated dependent on photon energy, temperature and applied electrical field in the threshold spectral region of intrinsic photogeneration in Pc crystals. The simulation results are shown to be in good agreement with experimental data and may be interpreted in terms of an adiabatic nearly-small molecular polaron approach. The polaron effective mass is shown to increase exponentially with temperature T reaching values of m eff=(10 2–10 3) m c in the 165–300 K temperature range, whilst the microscopic mobility of the polaron decreases as μ oα T −=, typical for anthracene-type crystals.