Simple accurate system for measuring absolute photoluminescence quantum efficiency in organic solid-state thin films

We accurately measured the absolute photoluminescence (PL) quantum efficiency (eta(PL)) of organic solid-state thin films using an integrating sphere. We particularly measured the eta(PL) of conventional organic materials used in organic light emitting. diodes, such as a tris(8-quinolionolato)aluminum(III) complex (Alq(3)), and a 2 wt%-fac-tris(2-phenylpyridyl)iridium(III): 4,4'-bis(carbazol-9-yl)-2,2'-biphenyl [Ir(ppy)(3):CBP] co-deposited film. Alq(3) and Ir(ppy)(3):CBP showed a eta(PL) = 20 +/- 1% and 97 +/- 2%, which corresponded well to external electroluminescence efficiency using these materials. We also measured their transient PL decay and determined the radiative rate constants with their eta(PL).