Masami Sugiuchi

Effect of polymer matrices on charge transport in molecularly doped polymers

Hole mobilities have been measured in diethylamino‐benzaldehyde‐diphenylhydrazone (DEH)‐doped polymers as a function of the polymer composition, temperature, and electric field. It was found that the electric field dependence on the mobility was a strong function of the binder polymer employed. In all cases, the electric field dependence E can be described as exp(βE1/2T−1). β2 is related to the density of photoinduced spins in the molecularly doped polymers, which are related to the interaction between DEH and the polymer.

Carrier generation in fullerenes

The efficiency of carrier generation by the zerographic discharge technique has been measured on four films; a molecularly C60-doped polymer film, a molecularly C70-doped polymer film, an aggregate C60 film, and an aggregate C70 film. The yield for molecularly C70-doped polymer was three orders of magnitude larger than that for the film of molecularly C60-doped polymer. The photon energy dependence of efficiency for the aggregate films differed from that for the molecularly doped polymer films. The carrier generation efficiency spectrum for the aggregate films showed peaks corresponding to the Frenkel type excitons. The sensitivity of a photoreceptor fabricated with C70 was 0.5(cm2/(mu) J) at wavelengths in the 420nm-670nm region.

Diffusion and drift of charge carriers in molecularly doped polymers

A transport equation has been fitted to time-of-flight transient photocurrent signals of molecularly doped polymers in order to obtain both diffusion coefficient (D) and drift mobility ((mu) ) simultaneously. The logarithm of (mu) increased linearly with the square root of the electric field. The negative field dependence on the square root of the electric field at a low electric field that had been reported appeared to superimposing of drift and diffusion. The logarithm of D increased linearly with the square root of the electric field. The logarithm of D decreased linearly with T-2.