Absolute photoluminescence yield in color converters for organic light-emitting diodes

The main focus of this thesis project is to develop a PL quantum efficiency measurement method for color converter thin film in OLED applications and to investigate the concentration effect of dye pair (Courmarin 334 with Pyrromethene 580) on the PL quantum efficiency for the two-dye system. The PL quantum efficiency was measured using a modified integrating-sphere method. The doping of a small amount of Pyrromethene 580 (0.1 wt%) into the host Courmarin 334 results in a twofold increase in PL quantum efficiency. The PL quantum efficiency of the two-dye system strongly depended on the concentration of Courmarin 334 but weakly on that of Pyrromethene 580. The two dye system has the maximum PL quantum efficiency when the concentration of Pyrromethene 580 is around 0.5% wt percent for a fixed concentration of C334. Based on the Forster energy transfer model, it is found 90% of the absorbed energy is released by the two competing mechanisms: Pyrromethene 580 radiative emission and Courmarin 334 non-radiative emission.