abstract |
The invention relates to spiro compounds of the formula (I) wherein at least one of the radicals K1, L, M, N?1, R1, R2, R3, R4¿ is one of the groups (a), (b), (c), (d), (e), (f), (g), (h), (i), (j) and (k). Said spiro compounds are suitable for use as charge transfer materials, especially for photovoltaic cells, and as electroluminescence materials. |