This study examined the electro-optical properties of black-background, normally transparent polymer network liquid crystal cells suitable for light shutters applicable to transparent flexible displays. The cells were fabricated using a polymer induced phase separation method from the mixture of negative liquid crystal, reactive-mesogen and black dye. A parametric study for key material and process parameters was carried out to determine the parameter dependence of the E-O properties and to achieve high E-O performance. The E-O properties were strongly dependent on RM concentration and UV exposure intensity, not on UV exposure energy. The optimal conditions for high E-O performance are described.