Crack-free TiO2 thin films with selfassembling nano-particles fabricated through in-situ sol–gel processing in reverse micelles

A simple strategy of combining in-situ reaction with microemulsion is used to prepare a crack-free TiO2 thin film with the nano-particles self-assembling into a mesoporous network. The particle shape and size are controlled by the reverse micelles in the microemulsion. In-situ growth of the TiO2 nano-particles prevents the film from cracking by reducing the build-up of capillary stress during the drying process. SEM images indicate that the in-situ TiO2 film is composed of interconnected nano-particles with a size of several tens of nanometers and does not crack macroscopically even when the film thickness is beyond 50 μm.

► In-situ growth of nano-particles greatly reduced shrinkage stress in gel network.
► No cracking was brought up in the TiO2 gel network during the process of heat treatment.
► TiO2 nano-particles self-assembled into a homogeneous mesoporous network.
► The TiO2 film remained crack-free even if the film thickness was beyond 50 μm.