Trap-induced light enhancement from a polymer light emitting device

In this work, a series of poly(p-phenylene benzobisoxazole) (PBO) light emitting devices was fabricated. Doping non-fluorescent copper phthalocyanine into the PBO light emitting layer caused a substantial enhancement in electroluminescence from the PBO matrix. Current-voltage characteristics revealed hole-trapping at low doping levels, and hole-transportation at high doping concentrations. The performance of the device improved substantially, reaching a brightness of 3.4 x 10(4) cd/m(2) and current efficiency of 10.9 cd/A or more. This offers a practical approach to develop a single-layered device structure by simply tuning the trap densities. (C) 2013 AIP Publishing LLC.