High-performance light diffuser films by hierarchical buckling-based surface texturing combined with internal pores generated from physical gelation induced phase separation of binary polymer solution

A simple and low-cost process has been demonstrated for the fabrication of high-performance light diffuser films. Instead of polymer composites with light diffusing micro/nanoparticles as in typical approaches, low refractive-index (RI) air pockets or pores have been included inside the diffuser film, which has large RI contrast to host polymer matrix. The generation of such pores has been enabled by elastomeric polydimethylsiloxane (PDMS) assisted fast drying of binary polymer solution, where physical gelation induced phase separation generates pores inside the dried film. To further increase the light scattering and thus the optical haze of such diffuser films, hierarchical buckling of PDMS surface by oxygen plasma treatment has been applied. The buckled PDMS could be directly integrated into the PDMS-assisted drying process, thereby enables one to fabricate high-performance diffuser films having both surface-relief patterns and internal pores at the same time. This unique combination of surface and volume scatterings has yielded high-performance light diffusing films with high transmittance and haze simultaneously.