Simultaneous measurement of the transient photoconductivity and photoluminescence in Alq3

We present a unique and simple technique which allows one to measure the transient photoluminescence (PL) and transient photoconductivity (PC) of thin film materials simultaneously. This technique will be useful in characterizing thin film materials that have a relatively high PL quantum yield, such as those used in EL devices (i.e. metal chelates, polymers, dyepolymer composite, etc.). The photogeneration of charge carriers and radiative excited states in pristine tris-(8-hyaroxyquinoline) aluminum (Alq3) were studied by measuring both its photoconductive and photoluminescence response simultaneously, with subnanosecond resolution. 25 psec laser pulses at 355nm were used for excitation of an Auston switch with a 2–4 μm thick film of Alq3 vacuum-evaporated across the active region. Quantitative measurements of the dependence on laser intensity, and applied electric field were performed. A scheme for the photoprocess in Alq3 is presented.