Ozone Generators for Mould and Smells

This should be the perfect place to get some advice!

I am a landlord for some students in Wales, and as they have a 10 month tenancy, over the summer I go into the property and sort out any issues. Two of the main issues the properties generally suffer from is mould and bad smells. A fellow landlord suggested using an ozone generator as he claims that it will tackle both the mould and the smells.

Some of the ozone generators out there are pretty expensive so before I take the plunge I wanted to get some other points of view from people who have had experience with using them. Are they good air purifiers? Do they tackle the mould?

Thanks,
Martin