Simple Accurate System for Measuring Absolute Photoluminescence Quantum Efficiency in Organic Solid-State Thin Films

Abstract

We accurately measured the absolute photoluminescence (PL) quantum efficiency (ηPL) of organic solid-state thin films using an integrating sphere. We particularly measured the ηPL of conventional organic materials used in organic light emitting diodes, such as a tris(8-quinolionolato)aluminum(III) complex (Alq3), 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. Alq3 and Ir(ppy)3:CBP showed a ηPL=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 ηPL.