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Proceedings Paper

Effect of film morphology on oxygen and water interaction with copper phthalocyanine
Author(s): Eric S. Muckley; Nicholas Miller; Thomas Gredig; Ilia N. Ivanov
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Paper Abstract

Copper phthalocyanine (CuPc) films of thickness 25 nm and 100 nm were grown by thermal sublimation at 25°C, 150°C, and 250°C in order to vary morphology. Using a source-measure unit and a quartz crystal microbalance (QCM), we measured changes in electrical resistance and film mass in situ during exposure to controlled pulses of O2 and H2O vapor. Mass loading by O2 was enhanced by a factor of 5 in films deposited at 250°C, possibly due to the ~200°C CuPc α→β transition which allows higher O2 mobility between stacked molecules. While gas/vapor sorption occurred over timescales of < 10 minutes, resistance change occurred over timescales < 1 hour, suggesting that mass change occurs by rapid adsorption at active surface sites, whereas resistive response is dominated by slow diffusion of adsorbates into the film bulk. Resistive response generally increases with film deposition temperature due to increased porosity associated with larger crystalline domains. The 25 nm thick films exhibit higher resistive response than 100 nm thick films after an hour of O2/H2O exposure due to the smaller analyte diffusion length required for reaching the film/electrode interface. We found evidence of decoupling of CuPc from the gold-coated QCM crystal due to preferential adsorption of O2/H2O molecules on gold, which is consistent with findings of other studies.

Paper Details

Date Published: 27 September 2016
PDF: 9 pages
Proc. SPIE 9944, Organic Sensors and Bioelectronics IX, 99440V (27 September 2016); doi: 10.1117/12.2236514
Show Author Affiliations
Eric S. Muckley, Oak Ridge National Lab. (United States)
Univ. of Tennessee (United States)
Nicholas Miller, California State Univ., Long Beach (United States)
Thomas Gredig, California State Univ., Long Beach (United States)
Ilia N. Ivanov, Oak Ridge National Lab. (United States)

Published in SPIE Proceedings Vol. 9944:
Organic Sensors and Bioelectronics IX
Ioannis Kymissis; Ruth Shinar; Luisa Torsi, Editor(s)

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