Investigation on hole drift mobility in poly(n-hexylphenylsilane)

The hole drift mobility in poly(n-hexylphenylsilane) (PHPS) was observed ov er an extended range of temperature and field by DC time-of-flight techniqu e. The value of the hole drift mobility in PHPS decreases monotonically fro m 6 x 10(-3) to 7 X 10(-4) cm(2)/V s with an increase in the field from 3 X 10(2) to 8 X 10(2) V/cm. A negative differential conduction model giving a good interpretation for the decrease in the mobility. The value of mobilit y was quantitatively analyzed based on Bassler's disorder formalism, giving a very small value of sigma = 0.042 eV in spite of the relatively large va lue of Sigma = 3.3. The polaron formation energy was also estimated to be E -p = 0.058 eV using the Bassler-Borsenberger' s equation. This value is ver y small value in comparison to that in poly(methylphenylsilane) (PMPS) and reflects that the backbone in PHPS is more tightly locked than that in PMPS . (C) 2000 Published by Elsevier Science Ltd. All rights reserved.