Share Email Print

Proceedings Paper

New method for obtaining drift mobility and diffusion coefficient and their relation in photorefractive polymers
Author(s): Akiko Hirao; Hideyuki Nishizawa; Takayuki Tsukamoto; Kazuki Matsumoto
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

A new easy method for obtaining a drift mobility and a diffusion coefficient from a nondispersive time-of-flight transient has been developed. Nondispersive transients are described well in the theoretical photocurrent equation (PTE) based on the fact that a carrier packet drifts at a constant velocity and is spread by diffusion, the top electrode acts as a reflecting and partially absorbing wall, and the counter electrode acts as an absorbing wall. The fitting of the PTE to photocurrent transients gives the mobility and the diffusion coefficient (D) simultaneously. These are suitable characteristic values for descriptions of carriers transport because they do not show the thickness dependence and the negative field dependence in a low electric field. The mobility that sometimes shows the thickness dependence and the negative field dependence in a low electric field, however, has usually been measured from the time of the intersection of the asymptotes to the plateau and trailing edge of the transients. In order to obtain (mu) a from photocurrent transients by a simple method, we have tried to describe t0 and tail-broadening parameter W as functions of (mu) a and D, where W is defined as (t1/2 - t0)/t1/2 and t1/2 is the time at which the current is a half of that in the plateau region. The dependences of calculated (mu) k and W on the electric field and the sample thickness agreed well with those of the experimental data. These results verify the PTE and suggest that (mu) a and D can be calculated from t0 and W. We also report that the diffusion coefficient is proportional to the power of 2 of the mobility. This result agrees with a theory based on the Langevin equation which describes motions of carriers in a fluctuated field.

Paper Details

Date Published: 5 October 1999
PDF: 11 pages
Proc. SPIE 3799, Organic Photorefractives, Photoreceptors, Waveguides, and Fibers, (5 October 1999); doi: 10.1117/12.363883
Show Author Affiliations
Akiko Hirao, Toshiba Corp. (Japan)
Hideyuki Nishizawa, Toshiba Corp. (Japan)
Takayuki Tsukamoto, Toshiba Corp. (Japan)
Kazuki Matsumoto, Toshiba Corp. (Japan)

Published in SPIE Proceedings Vol. 3799:
Organic Photorefractives, Photoreceptors, Waveguides, and Fibers
David H. Dunlap; Stephen Ducharme; Robert A. Norwood; David H. Dunlap; Robert A. Norwood, Editor(s)

© SPIE. Terms of Use
Back to Top
Sign in to read the full article
Create a free SPIE account to get access to
premium articles and original research
Forgot your username?