Process for two-dimensionally concentrating light, and novel perylene-3,4,9,10-tetracarboxylic acid diimides

Abstract

A process for concentrating light by means of fluorescent compounds of the formula ##STR1## where the R.sup.1 's independently of one another are ortho-substituted aromatic or heterocyclic radicals which do not contain groups which confer solubility in water, and novel perylene-3,4,9,10-tetracarboxylic acid diimides of the formula I, where R.sup.1 is ##STR2## A.sup.1 and A.sup.2 being hydrogen, or one of A.sup.1 or A.sup.2 being isopropyl and the other being hydrogen. The compounds I are very lightfast and convert incident light into fluorescent light with high efficiency.

Dependencies are inferred from the claim text.