A method of production of a thin film electroluminescent device comprising the steps of: providing a substrate; providing a conductor on the substrate; providing a dielectric layer on the conductor; providing a phosphor layer on the dielectric layer so creating a phosphor/dielectric interface region, the phosphor/dielectric region interface comprising a plurality of electron interface states; and transiently laser annealing the phosphor layer so as to induce an in depth annealing effect to the phosphor layer without heating the phosphor/dielectric region above a temperature which includes a substantial modification in the distribution of electron interface states.