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Volume: 43 | Article ID: art00006
Suitable Definition of Drift Mobility
  DOI :  10.2352/J.ImagingSci.Technol.1999.43.3.art00006  Published OnlineMay 1999

Measurement of the drift mobility defined as the proportionality constant of the mean velocity (v) to the electric field strength (E) is necessary for understanding of carrier transport. However, it is difficult to obtain v from the time-of-flight transients. Thus the velocity obtained from the transit time has been analyzed instead of the mean velocity. The most common measurement of the mobility (μk_ex) is obtained from the time derived from the intersection of the asymptotes to the plateau and tail of the transients. Because the long tail of photocurrent transients for molecularly doped polymers indicates anomalous dispersion of carrier transit times, the difference between ν/E and μk_ex is not negligible. Recently, a theoretical photocurrent transients equation (PTE) has been introduced. Fitting of the PTE to nondispersive transients gives the values of ν and the diffusion coefficient (D) simultaneously. In this article, using the PTE, both the mobility (μk_cal), obtained from a kink in the photocurrent transient, and the tail-broadening parameter (Wcal) were derived as functions of ν, D and sample thickness. We have tried to explain the anomalous behavior of μk_ex and the tail-broaden-ing parameter (Wex) in order to verify the PTE. The dependences of μk_ex and Wcal on the electric field and the sample thickness satisfactory agreed with those of μk_ex and Wex. These verify the PTE and suggest that fitting of the PTE to photocurrent transients is suitable way to obtain the drift mobility.

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A. Hirao, T. Tsukamoto, H. Nishizawa, "Suitable Definition of Drift Mobilityin Journal of Imaging Science and Technology,  1999,  pp 228 - 232,

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Copyright © Society for Imaging Science and Technology 1999
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