A new concept of inorganic nanoparticle dopant into organic hole transporting materials (HTM) is proposed for the design of semiconducting composites. Composites consisting of HTM and TiO2 nanoparticles were prepared using a polymer as a matrix. TiO2 nanoparticles were prepared by sol-gel method starting from titanium tetraisopropoxide. The particle size of TiO2 ranged from 2 to 5 nm. It was found that electrons were transferred from HTM to TiO2, leaving holes in HTM. The composites showed semiconducting characteristics with the conductivity on the order of 10(-8) S/cm. A device consisting of ITO/composite/Al showed rectifying ability. The number of the holes was approximately one per 7 X 10(5) molecules of N,N,N',N'-tetraphenylbenzidine (TPD) for the composite consisting of polycarbonate, TPD and TiO2 with the weight ratio of 100:100:3. (C) 2003 Elsevier B.V All rights reserved.