Organic light-emitting diodes with an internal light extraction layer prepared by intense pulsed light

An organic light-emitting device with an internal light extraction layer annealed with the intense pulsed light was fabricated. The internal light extraction layer was fabricated by annealing a dispersed solution of high-refractive index nano-particles (TiO2 and a TiO2:ZnO blend) using high-intensity pulsed light capable of low-temperature and high-speed processing. The differences in morphology between samples annealed by intense pulsed light (IPL) and that annealed by conventional heat treatment were studied. IPL annealed devices showed similar performance to that of thermally annealed devices. A planarization layer was required due to the roughness of the nano-size particles. A better heat-resistant and chemical-resistant polymer, poly(9-vinylcarbazole), was used in the planarization layer. The light extraction efficiency increased about four times in glass substrate devices and approximately doubled in plastic (PEN) substrate devices.