Highly efficient organic light-emitting devices based on multifunctional nanoparticles

We have constructed a new approach to realize the light extraction enhancement in organic light-emitting diodes (OLEDs) by using Fe3O4@Au nanoparticles (FOA NPs). The current efficiency of 97.8 cd/A at a luminance of 500 cd/m2 can be obtained for the FOA-NP-based device, while it is only 61 cd/A for the control device without FOA NPs, corresponding a 60% enhancement in efficiency. The time-resolved photoluminescence and optical haze characterizations were performed to study the influence of FOA NPs on the lifetime of excitons and the light-scattering effect, respectively. These results reveal that the enhanced radical efficiency of an FOA-NP-based device is mainly ascribed to the localized surface plasmonic effects induced by Au NPs and the strong light-scattering effect related to FOA NPs, thereby achieving a double enhancement in light extraction, which paves a new way in realizing high-efficiency and controllable OLEDs.