Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles

Highly efficient inverted polymer light-emitting diodes using surface modifications of ZnO layer

“…In the case of ZnO-F and ZnO-R1 devices, the amount of power emitted directly to air (k x ok n_air ¼ 1 ) is increased from 19 to 34% and the optical loss including waveguided and SPP modes (k x 4k n_glass ¼ 1.52 ) is decreased from 35 to 26%. It implies that the enhancement of extraction efficiency is about 79% for the iPLED with ZnO-R1 compared with ZnO-F. We believe that the extraction is primarily attributable to the reduction in the in-plane wave vectors of the WG modes caused by the Bragg grating vector 7,8 . To clarify the higher extraction in the ZnO-R1 device (L ¼ 300 nm) compared with that in the ZnO-R2 device (L ¼ 600 nm), we calculated the grating period as a function of the emission wavelength, as shown in Supplementary Fig.…”

“…In conventionally-structured PLEDs, Z e is particularly poor at approximately 20% because the light generated in the emissive semiconductor is trapped and waveguided inside the OLEDs/PLEDs [4][5][6][7][8] .…”

Repurposing Blu-ray movie discs as quasi-random nanoimprinting templates for photon management

“…These disordered structures have received renewed interest for photon management in a variety of engineering applications, such as highly efficient photon extraction in light-emitting diodes 8 , biomimetic structural coloration 5,9 and random lasing 10,11 . Unlike perfectly periodic [12][13][14][15][16] or totally random structures, quasi-random nanostructures can offer both broadband absorption enhancement and customizable spectral response for different photoactive materials 4,[17][18][19] .…”

Surface plasmon-enhanced electroluminescence in organic light-emitting diodes incorporating Au nanoparticles

“…[4][5][6] However, the poor light extraction efficiency of $20% in a conventional OLED limits the external quantum efficiency due to the total internal reflection (TIR) at the glass substrate/air and indium-tinoxide (ITO)/substrate interfaces, the waveguide (WG) mode at the organic/ITO anode interface, and the surface plasmon (SP) losses at the metallic cathode/organic interface. [7][8][9][10] Various methods have been proposed to enhance light out-coupling in OLEDs, including surface microstructures on ITO anode to reduce the WG mode loss, 11,12 photonic crystals or microlens arrays attached on the glass substrate for the reduction of TIR, 13,14 corrugated cathode to reduce SP losses, [15][16][17][18] optical microcavity structures, 19 and so on. Recently, the localized SP effect excited by metallic nanostructures is becoming one of the most attractive approaches for light emission enhancement in OLEDs through the coupling with localized SP resonance and the emission energy.…”

“…Recently, the localized SP effect excited by metallic nanostructures is becoming one of the most attractive approaches for light emission enhancement in OLEDs through the coupling with localized SP resonance and the emission energy. [15][16][17][18]20,21 For example, Koo et al have demonstrated the enhancement of light extraction efficiency in OLEDs by a quasi-periodic buckling structure without introducing spectral changes and directionality. 15 The roughness on the cathode side induced by lithography process 16 or template transform 15 can match the momentum of SPs and radiated light, leading to the SP enhancement.…”