| 摘要 |
Spiro compounds of the formula (I),where X1, X2, X3, X4 are identical or different and are -S-, -O-, -NR5-, -CR5=N- or -CR5=CH-, with the proviso that at least one of the groups X1-4 is different from -CR5=CH-, are suitable as charge transport materials, in particular for photovoltaic cells, and as electroluminescence materials.
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