Formation, structure and photoelectrical properties of poly-p-xylylene-PbSsemiconductor nanocomposite films

Poly-p-xylylene-PbS nanocomposite films were synthesized by simultaneous lo w-temperature cocondensation of p-xylylene and PbS vapors. Structure of hig hly dispersed poly-p-xylylene-PbS composites was studied by UV-Vis spectros copy and by X-ray method. It was established that PbS forms the nanocrystal s of 4 nm highly dispersed in amorphous regions of poly-p-xylylene (PPX). I t has been shown that the arrangement of nanocrystals in composite films is determined by poly-p-xylylene supramolecular structure: PbS nanocrystals a re localized in the poly-p-xylylene amorphous regions characterized by high free volume. Dark conductivity decreases at long-term storage of film that probably results from the diffusion and rearrangement of PbS clusters in a morphous regions. Synthesized PbS composites reveal the essential photocond uctive effect. Low energy of excited light, the temperature and voltage dep endence of observed photoconductivity lead to the conclusion that the condu ctivity is determined by the photostimulated tunnel electron transfer betwe en semiconductor-nanocrystals. (C) 1999 Published by Elsevier Science S.A. All rights reserved.