The effect of gases on the conductive properties of organic semiconductors. Part 5: Results for films of chloranil, phenanthrene, phenazine, phtalocyanine (metal free) and crystal violet

The effect of gases on the dark and photoconductivity of various compounds was investigated to determine suitability of these compounds for detecting, sensitively and selectively, atmospheric contaminants. Results indicate that the changes of the dark conductivities of the investigated compounds are large on adsorption of several gases; however, the reproducibility, sensitivity, and selectivity seem insufficient for contructing a reliable multicomponent gas detector on this basis. Selectivity is improved by considering data from photoconductivity measurements. Sensitivity and response time of the semiconductors investigated are reasonable for strong electron donating and electron accepting gases. For weak electron donating and electron accepting gases, no significant effect was measured. The reversibility of gas adsorption on the semiconductor surfaces is poor, especially in the case of very aggressive gases.