Decay mechanisms of passive matrix organic light-emitting diode display

A 102X64 monochromatic passive matrix organic light-emitting diode (PMOLED) display was studied for its decay process. The structure of the device was ITO(indium tin oxide)/CuPc (copper phthalocyanine/NPB(N,N '-di(naphthalene-1-yl)-N,N '-diphenyl-benzidine)/Alq(3)(tris-(8hydroxyqu-inoline)aluminum):C545(coumarin)/Alq(3)/LiF/Al. We carried out a vision inspection and electrical (I-V) and optical characterizations, analyzed the EL (electroluminescence) and PL (photoluminescence) spectra before and after the aging test. The aged device under constant current appeared higher driving voltage, smaller leak current, lower EL and PL intensities which were come from the peeling of cathode/organic layers, the burning of shorted routes between the electrodes and the decomposition of light-emitting materials. The EL intensity remains 75.6% while the PL does 81.4% of their initials values after 17 hours aging, which means the EL and PL decay simultaneously, i.e. the decomposition of emissive material is dominant in the decay process and results in the permanent damage in the display panel.