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Proceedings Paper

Polymer-based photodetectors for structurally integrated photoluminescence based oxygen sensors
Author(s): Kanwar S. Nalwa; Yuankun Cai; Aaron L. Thoeming; Ruth Shinar; Joseph Shinar; Sumit Chaudhary
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Paper Abstract

A photoluminescence (PL)-based O2 sensor utilizing inorganic light emitting diode (LED) as the light source and a polymer-based photodetector (PD) is demonstrated. The device structure is compact and the sensor integrates the sensing element, light source, and organic PD as thin films that are attached such that the sensing element is sandwiched between the LED and the PD. The sensing elements are based on the oxygen-sensitive dyes Pt-octaethylporphyrin embedded in a polystyrene matrix. A green inorganic LED (peak emission ~525 nm) light source was used to excite the porphyrin dye, which emits at ~640 nm. This emission can be measured using P3HT:PCBM bulk heterojunction photodiodes, which have been shown earlier to have efficient photodetection at this wavelength if the active layer is sufficiently thick. The time constant associated with sweeping out the photogenerated carriers is found to be ~ 10μs. Such a fast decay of photocurrent is useful for oxygen monitoring, determined by measuring the Pl decay time rather than the PL intensity, of the sensing film. This approach can eliminate the need for frequent sensor calibration and optical filters (as pulsed LED excitation is employed in this mode) which lead to bulkier design.

Paper Details

Date Published: 27 August 2009
PDF: 7 pages
Proc. SPIE 7418, Organic Semiconductors in Sensors and Bioelectronics II, 74180F (27 August 2009); doi: 10.1117/12.830101
Show Author Affiliations
Kanwar S. Nalwa, Iowa State Univ. (United States)
Yuankun Cai, Ames Lab. (United States)
Aaron L. Thoeming, Iowa State Univ (United States)
Ruth Shinar, Iowa State Univ. (United States)
Joseph Shinar, Ames Lab. (United States)
Sumit Chaudhary, Iowa State Univ. (United States)
Ames Lab. (United States)

Published in SPIE Proceedings Vol. 7418:
Organic Semiconductors in Sensors and Bioelectronics II
Ruth Shinar; George G. Malliaras, Editor(s)

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