Stratified LCDs: Paintable LCDs produced by photo-enforced stratification

The "Paintable LCD" approach allows the preparation of an LCD on a single substrate by the sequential coating and curing of a stack of tailored organic layers. This revolutionary new technology for the manufacturing of liquid crystal displays (LCDs) provides freedom in display design as well as in production methodology. In fact, displays can be prepared on any substrate. The key process that enables layer stacking on top of the liquid crystal (LC) layer is called photo-enforced stratification (PES). It comprises a two-step photopolymerisation-induced phase-separation of an LC blend and a polymer precursor. In these polymerization steps, the single thin layer (a homogeneous mixture of an LC blend and a polymer precursor) very accurately phase-separates in a hard polymer top coat and a pure LC layer underneath. Directionality with respect to the phase-separation can be achieved by using the absorption of one of the compounds in the mixture which provides a UV intensity gradient over the layer thickness. As a result, the photopolymerisation predominantly takes place where the UV intensity is the highest i.e. near the film surface that is directed towards the UV source. Also other optical layers, like polarisers or retarders, can be deposited by simple coating techniques, so that the complete display can be made using one, very simple and versatile, technology.