Electrical measurement on a phthalocyanine Langmuir-Blodgett film: I. Comprehensive studies on the origins of scattering and drift of resistance values

The semi-conducting properties of an organic Langmuir-Blodgett (LB) film ha ve been investigated using two configurations of LB film and electrodes. Th e studied material is the copper tetraoctadecyltetrapyridino [3,4-b:3',4'-g :3",4"-1:3''',4'''-q] porphyrazinium bromide (CuS18). The scattering of res istance values appears to be dependent on the configuration. Films in the ' down' configuration (electrodes under the LB film) present resistance value s that are less scattered but higher than the ones of films in the 'top' co nfiguration (electrodes over the LB film). The good but less reproducible c ontact which is observed in the 'top' configuration is certainly provided b y the penetration of gold atoms inside the organic him. Similarly, a study on the factors which influence the stability of organic/inorganic devices s uggests that these factors originate from material structural evolution mai nly near the shadow area of the electrodes.