In this thesis , we studied the photo-chemistry between the green emitter (C545T) and the photo-acid generator (PAG) . When the sample of C545T and PAG in solutions and thin films were exposured to UV-light , we found that a new product was produced due to protonation of C545T with the acid generated by PAG . Therefore , we measured absorption and fluorescence spectra of the samples in solutions (THF) and in polymer (PMMA) thin films . The different concentrations of C545T dopanted photo-acid generator in the solvent (THF) could increase the photo-acid generator at higher concentrations of PAG , the energy could be transferred from unprotonated to protonated . Therefore , we can easily observe the absorption and fluorescence spectra have been changed and the phenomenon of stock¡¦s shift has been found accordingly . At higher concentrations of C545T in solutions , also called concentrations quenching effect was observed because C545T molecules could collide each other easily that causes intensity to decrease in the solvent (THF) . In order to get rid of the collision effect , we use the samples of polymer thin films instead of solutions . The different of the change of spectra between solutions and thin films were observed and compared were also studied .