Performance enhancement of organic light-emitting diode by heat treatment

The effects of post-fabrication heat treatments on the performance and stability of organic light-emitting diodes (OLEDs) were studied in standard NPB/Alq3 devices. Electroluminescence (EL) performance, growth of dark spots, and operation stability of the devices with different heat-treatments were measured and monitored. It was found that optimum thermal treatment can slow down the growth of dark-spot and luminescence degradation in the OLEDs. Substantial increase in operation lifetime was also observed in the heat-treated samples. Heating at 70 °C for 7.5 min increases the half-brightness lifetime from 6400 h (untreated device) to over 15,000 h.