Some authors consider structures perovskite type to any structure ABX3 type, however in inorganic chemistry it is established that it is necessary that the atomic radius of cation A is preferably double to cation B. In any case that the cation A and B are of size similar, the type of structure is called Ilmenite. Given the above, why consider perovskite type structure to the "hybrid perovskites", when the Cation does not exist, being this a molecule?

Or is it necessary to make a new definition of perovskyta type structure? Taking into account that the model structure is CaTiO3

Give your opinion about it.