Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10618730 | Synthetic Metals | 2005 | 4 Pages |
Abstract
We present detailed continuous wave (cw) and transient photoinduced absorption (PA) measurements in thin films of a novel alternating polyfluorene copolymer, poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4â²,7â²-di-2-thienyl-2â²,1â²,3-benzo-thiadiazole)] (DiO-PFDTBT), and its blends with the soluble fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) in weight ratios of 1:0, 4:1 and 1:4. We measure the frequency, intensity and temperature dependence of the PA signal in the frequency domain, and compare with the results obtained from the transient PA decay measurements in the time domain. In all blends, the PA spectrum shows a broad high energy PA band ranging from â¼1Â eV to 2Â eV as well as a low energy band peaking at â¼0.35Â eV. We attribute the low energy band to the P1 transition of polarons and part of the high energy band to the correlated P2 transition of polarons. Both frequency and time domain measurements show that the high energy band has two decay components, a faster component in the microsecond time regime and a slower component in the millisecond time regime. The slow component is strongly dispersive, whereas the fast component is practically non-dispersive.
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Physical Sciences and Engineering
Materials Science
Biomaterials
Authors
Harri Aarnio, Markus Westerling, Ronald Ãsterbacka, Mattias Svensson, Mats R. Andersson, Torbjörn Pascher, Jinxi Pan, Villy Sundström, Henrik Stubb,