Charge carrier mobility in an organic-inorganic hybrid nanocomposite

Organic-inorganic hybrid materials are media for electronic and optoelectronic applications. We present a study of the electronic transport in such a model nanoparticle-sensitized hybrid organic-inorganic photorefractive host system, consisting of poly(N-vinylcarbazole) doped with quantum dots of cadmium sulfide, using standard time-of-flight techniques. The photocurrent transients exhibit features typical of dispersive transport in an amorphous semiconductor. The hole mobility depends strongly on the electric field and temperature indicating Poole-Frenkel-like activated hopping transport; a thickness dependence of the mobility is observed. The presence of nanoparticles does not lead to increased trapping of holes. Conversely, a surprising result is observed: the mobility actually increases with the increase of nanoparticle concentration even though it is well below the percolation limit. (C) 2003 American Institute of Physics.