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Dillon RJ, Bardeen CJ. Time-resolved studies of charge recombination in the pyrene/TCNQ charge-transfer crystal: evidence for tunneling. J Phys Chem A 2012; 116:5145-50. [PMID: 22591413 DOI: 10.1021/jp302829a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous studies of solid-state tetracyanobenzene-based donor-acceptor complexes showed that these materials were highly susceptible to both laser and mechanical damage that complicated the analysis of their electron-transfer kinetics. In this paper, we characterize the optical properties of a pyrene/tetracyanoquinodimethane charge-transfer crystal that is much more robust than the tetracyanobenzene compounds. This donor-acceptor complex has a charge-transfer absorption that extends into the near-infrared, rendering the crystal black. We use time-resolved fluorescence and diffuse reflectance transient absorption to study its dynamics after photoexcitation. We show that the initially excited charge-transfer state undergoes a rapid, monoexponential decay with a lifetime of 290 ps at room temperature. There is no evidence for any long-lived intermediate or dark states; therefore, this decay is attributed to charge recombination back to the ground state. Fluorescence lifetime measurements demonstrate that this process becomes temperature-independent below 60 K, indicative of a thermally activated tunneling mechanism. The subnanosecond charge recombination makes this low-band-gap donor-acceptor material a poor candidate for generating long-lived electron-hole pairs.
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Affiliation(s)
- Robert J Dillon
- Department of Chemistry, University of California, Riverside, Riverside, California 92521, USA
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Wang Y, Nichogi K, Terashita SI, Iriyama K, Ozaki Y. Dependences of Thermal Behaviors on the Number of Layers in Langmuir−Blodgett Films of 2-Octadecyl-7,7,8,8-tetracyanoquinodimethane. 1. Order−Disorder Transitions in the Films Investigated by Ultraviolet−Visible and Infrared Spectroscopies. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp952163t] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yan Wang
- Department of Chemistry, School of Science, Kwansei-Gakuin University, Uegahara, Nishinomiya 662, Japan, Advanced Materials Research Laboratory, Matsushita Research Institute Tokyo, Inc., Higashimaita, Tama-ku, Kawasaki 214, Japan, and Division of Biochemistry, Institute of Medical Science, The Jikei University School of Medicine, Nishi-shinbashi, Minato-ku, Tokyo 105, Japan
| | - Katsuhiro Nichogi
- Department of Chemistry, School of Science, Kwansei-Gakuin University, Uegahara, Nishinomiya 662, Japan, Advanced Materials Research Laboratory, Matsushita Research Institute Tokyo, Inc., Higashimaita, Tama-ku, Kawasaki 214, Japan, and Division of Biochemistry, Institute of Medical Science, The Jikei University School of Medicine, Nishi-shinbashi, Minato-ku, Tokyo 105, Japan
| | - Shin-ichi Terashita
- Department of Chemistry, School of Science, Kwansei-Gakuin University, Uegahara, Nishinomiya 662, Japan, Advanced Materials Research Laboratory, Matsushita Research Institute Tokyo, Inc., Higashimaita, Tama-ku, Kawasaki 214, Japan, and Division of Biochemistry, Institute of Medical Science, The Jikei University School of Medicine, Nishi-shinbashi, Minato-ku, Tokyo 105, Japan
| | - Keiji Iriyama
- Department of Chemistry, School of Science, Kwansei-Gakuin University, Uegahara, Nishinomiya 662, Japan, Advanced Materials Research Laboratory, Matsushita Research Institute Tokyo, Inc., Higashimaita, Tama-ku, Kawasaki 214, Japan, and Division of Biochemistry, Institute of Medical Science, The Jikei University School of Medicine, Nishi-shinbashi, Minato-ku, Tokyo 105, Japan
| | - Yukihiro Ozaki
- Department of Chemistry, School of Science, Kwansei-Gakuin University, Uegahara, Nishinomiya 662, Japan, Advanced Materials Research Laboratory, Matsushita Research Institute Tokyo, Inc., Higashimaita, Tama-ku, Kawasaki 214, Japan, and Division of Biochemistry, Institute of Medical Science, The Jikei University School of Medicine, Nishi-shinbashi, Minato-ku, Tokyo 105, Japan
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