Photoluminescent properties in thin films of the proton-transfer laser dye, 2-(2-hydroxyphenyl)benzothiazole (HBT) were investigated, when it was doped into hole-transport polymer, poly(N-vinylcarbazole) and when it was codoped with hole-transport small molecule, N,N'-di(m-tolyl)-NN'-diphenylbenzidine (TPD) into polystyrene. The more the doping concentration of HBT was raised up to about 40 wt%. the more its photoluminescent intensity was enhanced without showing excimer or exciplex emissions. The mechanism for such phenomena was discussed in connection with the excited-state intramolecular proton-transfer reaction of HBT. (c) 2006 Elsevier B.V. All rights reserved.