Photogeneration of charge carriers and their transport properties in poly[bis(p-n-butylphenyl)silane]

The photocarrier generation mechanism and mobility in poly [bis(p-n-butylphenyl)silane] (PBPS) thin films doped with a variety of electron acceptors are studied by time-resolved microwave conductivity (TRMC) measurements. It was found that fullerene is a suitable electron acceptor for PBPS as it provides the highest product of photocarrier generation yield phi and mobility Sigma mu under excitation at 532 and 355 nm. The observed high phi Sigma mu value of 4.5 x 10(-3) cm(2)/(V s) under excitation at 193 nm (6.39 eV) can be attributed to the direct ionization of PBPS molecules. The photoinduced electron transfer between C-60 and PBPS was investigated in a solution sample by laser flash photolysis under excitation at 532 nm. On the basis of the extinction coefficient of PBPS center dot+, transient absorption of PBPS center dot+ provides a maximum value of phi of 0.83% for the electron-transfer reaction from PBPS to C-3(60)*. On the basis of this value of phi, the intrinsic intrachain mobility of holes on the PBPS backbone is estimated to be higher than 1.7 x 10(-2) cm(2)/(V s), suggesting the presence of a high conducting path along the Si backbone of PBPS.