Simultaneously Enhancing Color Spatial Uniformity and Operational Stability with Deterministic Quasi-periodic Nanocone Arrays for Tandem Organic Light-Emitting Diodes

An efficient tandem organic light-emitting diode is realized by employing a novel light out-coupling structure with deterministic quasi-periodic nanocone arrays. The enhancement of color spatial uniformity and operational stability is simultaneously realized along with the remarkable efficiency improvement in tandem devices by integrating multi-photon emission and light out-coupling techniques. The optimized tandem organic light-emitting diode with two emission units exhibits an enhancement factor of 4.99 and 10.49 for device efficiency and half-decay lifetime, respectively, as compared to the conventional device with a planar single-unit structure. Moreover, it is verified that the emission color with viewing angles was significantly stabilized with no apparent spectral distortion. Theoretical calculations clarify that the improved device performance is primarily attributed to the effective extraction of the waveguide and surface plasmonic modes of the confined light over all the emission wavelengths and viewing-angles. Highly efficient tandem OLEDs with simultaneously enhanced color spatial uniformity and operational stability are demonstrated by using deterministic quasi-periodic nanocone arrays for light out-coupling. The proposed light out-coupling structure can, remakably, extract the waveguide and surface plasmonic modes of the confined light over all emission wavelengths and angles.