Carrier Mobility in Polycarbonate Films Doped with Pyrazolines

Abstract

A charge transport in some pyrazolines dispersed in polycarbonate films was studied. Three pyrazolines with the same chemical composition but with different substitution sites for a pendant 1-naphthyl group, namely, 3-(1-naphthyl)-1, 5-diphenyl-2-pyrazoline (pyrazoline [2]), 5-(1-naphthyl)-1, 3-diphenyl-2-pyrazoline (pyrazoline[3]), and 1-(1-napht hyl)-3, 5dipheny1-2-pyrazoline (pyrazoline [1]) (Fig.1), were utilized. The absorption spectra and the photocurrent pectra (Figs.2 and 3) of the three pyrazolines in polymer matrices were examined. The absorption maximum in pyrazoline[2] was located at the longest wavelength of 385 nm. Also, pyrazoline[2] gave the largest photocurrent among three pyrazolines. The drift mobilities of holes in three pyrazolines in polymer matrices were evaluated by use of the conventional time-of-flight method. Pyrazoline[2] gave the largest mobility value when the three pyrazolines were compared at the same applied field (Fig.9). The localization radii of hopping sites were analyzed from the relation between carrier mobilities and the concentration of doped molecules (Fig.10). Pyrazoline[2] gave the largest localization radius of 0.17nm, while pyrazoline[1] and [3] gave 0.12 nm and O.15 nm, respectively.