Use of spiro compounds of the formula (I) ##STR1## where K.sup.1 and K.sup.2 are, independently of one another, conjugated systems, in electroluminescence devices. Preferred compounds of the formula (I) are 9,9'-spirobifluorene derivatives of the formula (II) ##STR2## where the benzo groups can be substituted independently of one another. Compounds of the formula (I) have a good solubility in customary organic solvents, improved film-forming properties and a significantly reduced tendency to crystallize. The production of electroluminescence devices is thereby made easier and their service life is increased.