SIMULTANEOUS MEASUREMENT OF THE TRANSIENT PHOTOCONDUCTIVITY AND PHOTOLUMINESCENCE IN ALQ(3)

We present a unique and simple technique which allows one to measure t he transient photoluminescence (PL) and transient photoconductivity (P C) of thin film materials simultaneously. This technique will be usefu l in characterizing thin film materials that have a relatively PL quan tum yield, such as those used in EL devices (i.e. metal chelates, poly mers, dye-polymer composite, etc.). The photogeneration of charge carr iers and radiative excited states in pristine tris-(8-hydroxyquinoline ) aluminum (Alq(3)) were studied by measuring both its photoconductive and photoluminescence response simultaneously, with subnanosecond res olution. 25 psec laser pulses at 355nm were used for excitation of an Auston switch with a 2-4 mu m thick film of Alq(3) vacuum-evaporated a cross the active region. Quantitative measurements of the dependence o n laser intensity, and applied electric field were performed. A scheme for the photoprocess in Alq3 is presented.