| abstract |
A coated material comprising a substrate which is coated with a layer of a pyrrolopyrrole of formula I ##STR1## wherein R 1 and R 2 may be 4-pyridyl and X 1 and X 2 are O, said compound of formula I being at least partially in the form of a salt of a strong acid, is suitable for use as an optical recording material and, owing to its electrical conductivity and photoconductivity, as antistatically treated material, as sensor, photoreceptor and solar battery. |