I read that Active tiles have self-cleaning properties. Could I avoid cleaning them if I used them in my house?
No. Self-cleaning means easier to clean so it is possible to use less aggressive detergents, or only water as well, for cleaning them, in that way you can save money and cause a lower environmental impact; indeed detergents are a source of water and air pollution because of they VOC (volatile organic compounds) release.
What does hydrophilicity means?
The term hydrophilic is usually referred to the ability of a material or a chemical species (such as molecules or particles) to interact with water. The term hydrophilic, in the widest sense, can also describe the ability of some materials to absorb and retain water on their surface or in their bulk.
When the titanium dioxide is exposed to light, it is able to attract and retain water (H2O).
By coating solid surfaces by titanium dioxide particles it is possible to confer them self-cleaning features, in fact the dirt hardly adhere on such hydrophilic surfaces. As a consequence the surface cleaning is easier ant the use of detergents (which are pollutant for the environment) is unnecessary