The invention provides a lighting device comprising (a) a light source, for producing light source light, and (b) a light converter, wherein the converter comprises a matrix of a first polymer, the matrix containing discrete regions comprising a second polymer with luminescent functionality, wherein the second polymer comprises an aromatic polyester comprising luminescent moieties, and wherein the first polymer is chemically different from the aromatic polyester. The invention also provides a light converter, wherein the converter comprises a matrix of a first polymer, the matrix containing discrete regions comprising a second polymer with luminescent functionality, wherein the second polymer comprises an aromatic polyester comprising luminescent moieties, and wherein the first polymer is chemically different from the aromatic polyester.