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Discotic Liquid Crystalline Porphyrins: Photophysical and Photoelectrical Properties of Large-Area Crystalline Films

Published online by Cambridge University Press:  25 February 2011

Brian A. Gregg ,
Marye Anne Fox  and
Allen J. Bard
Brian A. Gregg
Affiliation:
University of Texas at Austin, Dept. of Chemical Engineering, Austin, TX 78712.
Marye Anne Fox
Affiliation:
University of Texas at Austin, Dept. of Chemistry, Austin, TX 78712.
Allen J. Bard
Affiliation:
University of Texas at Austin, Dept. of Chemistry, Austin, TX 78712.
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Abstract

Porphyrins exhibiting discotic liquid crystalline phases have been developed in order to prepare thin, large-area, crystalline films of molecular conductors. A series of octaalkylporphyrins bearing different side chains have been synthesized including some with electron-withdrawing substituents at the meso positions. The photophysical properties of thin films of these compounds are a strong function of the film order (crystallinity). A substantial and persistent photovoltaic effect was achieved (e.g., Voc = 0.3 V, jsc = 0.4 mA/cm2 under white light, 150 mW/cm2) in capillary-filled symmetrical cells with indium-tin oxide electrodes. A model based on kinetically-controlled asymmetric exciton dissociation leading to photoinjection at the illuminated interface is presented to explain these results. This appears to be the first unambiguous example of a photovoltaic cell controlled entirely by interfacial kinetics. The predominance of the photoinjection process in these cells is attributed to the single-crystal-like character of the porphyrin films.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 173: Symposium Q – Advanced Organic Solid State Materials , 1989 , 199
Copyright
Copyright © Materials Research Society 1990

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References

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