This deals with a luminescent salt comprising a metal cluster anion and an organic cation, wherein the metal cluster anion comprises a metal cluster with at least two metal atoms, and ligands, the metal atoms being chosen from the group consisting of molybdenum, rhenium, tungsten, thallium, niobium, and mixtures thereof, wherein the organic cation comprises a cationic head substituted by at least one substituent including a polymerizable functional group. It also deals with a polymeric material comprising a polymer matrix which has polymerized with this luminescent salt.