559 K
17 pp.
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TitleMeasurements of Photo-induced Changes in Conjugated Polymers
Author(s)Seager, C. H.; Sinclair, M. B.; Mc Branch, D.; Heeger, A. J.; Baker, G. L.
Publication Date1991
Report NumberSAND-91-1000C
Unique IdentifierACC0472
Other NumbersCONF-910406--14; Legacy ID: DE91013262; OSTI ID: 5553662
Research OrgSandia National Laboratories, Albuquerque, NM (USA)
Contract NoAC04-76DP00789
Sponsoring OrgU.S. Department of Energy (DOE) Assistant Secretary for Defense Programs (DP), Washington, DC (USA)
Other InformationSpring meeting of the Materials Research Society (MRS), Anaheim, CA (USA), 29 Apr - 3 May 1991
Subject36 Materials Science; Polymers; Infrared Spectra; Absorption; Decay; Excitation; Light Transmission; Opacity; Polarons; Waveguides; Wavelengths; Energy-Level Transitions; Optical Properties; Physical Properties; Quasi Particles; Spectra
Related Web PagesAlan J. Heeger, Conductive Polymers, and Plastic Solar Cells
AbstractWe have used the highly sensitive technique of Photothermal Deflection Spectroscopy (PDS) to measure changes in the infrared absorption spectra of MEHPPV, P3HT and Polydiacetylene-4BCMU induced by pumping these polymers with light above the {pi} - {pi}* transition energy. In contrast to previous chopped light transmission measurements of these effects, the PDS technique can directly measure the buildup or decay of the absorption coefficient, {alpha}, on the time scale of second to days. In the case of MEHPPV we observe that the time scale of seconds to days. In the case of MEHPPV we observe that above-gap light causes the appearance of a broad infrared peak in {alpha}, which continues to grow-in hours after the pump light is first applied. For this polymer the general shape of the absorption spectra in the unpumped state mimics the photo-induced changes, suggesting that remnant photo-induced states determine the maximum transparency observed under normal experimental conditions. For P3HT and to a lesser extent, MEHPPV, we also observe irreversible photo-induced absorption components which we tentatively identify with photo-induced oxidation of the polymer matrix.
559 K
17 pp.
View Document 

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