Copolymers for luminescent enhancement in reflective display applications comprise a functionalized fluorene moiety, including a functional group selected from water-soluble functional groups and/or alcohol-soluble functional groups, and a heterocyclic ring moiety selected from the group consisting of substituted carbazole derivatives, substituted benzothiadiazole derivatives, and substituted phenothiazine derivatives, wherein the respective substituted derivatives include a functional group selected from water-soluble functional groups and/or alcohol-soluble functional groups. Composite materials comprising the copolymers and photoluminescent dyes are also provided, as is a luminescence-based sub-pixel (100).