Effect of the polyimide concentration on the memory stability of the silica-nanoparticle-doped hybrid aligned nematic cell

We investigate the stability of the memory state of the silica-nanoparticle-doped hybrid aligned nematic (SN-HAN) cell. The memory stability of the cell is attributed to the employed planar substrate, which is coated with a homogeneous polyimide (H-PI) film. A H-PI film with a low H-PI solid concentration gives the cell high memory stability. This is because the low H-PI solid concentration causes the film to have a high polar surface energy, trapping polar silica nanoparticles on the planar substrate tightly. The low H-PI solid concentration also gives the substrate a bumpy surface, which has a large surface area for trapping silica nanoparticles.