PHOTOELECTROCHEMICAL BEHAVIOR OF Q-STATE CDSXSE(1-X) PARTICLES IN ARACHIDIC ACID LANGMUIR-BLODGETT-FILMS

CdS Q-state particles, with mean diameters varying from 2 to 10 nm, gr own in arachidic acid Langmuir-Blodgett (LB) films, have been exposed to H2Se(g) to form the corresponding Q-state CdSxSe(1-x) particles. Th ese particles are considered to be made up of a core of CdS coated wit h about a monolayer of CdSe. Q-state CdSxSe(1-x) particle formation wa s verified by X-ray photoelectron spectroscopy (XPS) and by monitoring a red shift in the UV-VIS absorbance spectra relative to that of CdS. XPS results on 6 nm diameter CdS particles that had been grown in an LB film and then extensively exposed to H2Se(g), revealed a stable ave rage composition of CdS0.4Se0.6. A study of the photoelectrochemical b ehaviour of these systems was conducted through current-voltage polari sation curves in the range 0 to -1000 mV vs. SCE. An average drop of 1 00 mV in the open-circuit voltage and a marked increase in the short-c ircuit current was observed when LB films with Q-state CdS particles w ere exposed to H2Se(g). Evidence is also presented which shows that, a s the mean diameter of the core-shell particles increases from 2 to 10 nm, better connection between the particles in the film is achieved.