Light extraction from surface plasmon polaritons and substrate/waveguide modes in organic light-emitting devices with silver-nanomesh electrodes

Abstract

Light out-coupling of organic light-emitting diodes (OLEDs) with silver (Ag)-nanomesh electrodes was examined. Experimental results for the OLEDs with nine different nanomesh dimensions were compared with simulation results to elucidate the dimensional effect of the nanomesh on the light out-coupling behavior of the devices. The Ag-nanomesh electrodes did not only increase the transparency of the Ag electrode due to periodic nanoholes but also enhanced light extraction from surface plasmon polaritons and substrate/waveguide modes in the devices. The simulation results show similar trends with the experimental results for the optical transmittance, emission spectrum, and efficiency enhancement. With a nanomesh dimension of 480 nm period and 50% fill factor, the OLEDs with the Ag-nanomesh electrode showed 1.66 times higher efficiency than those with a planar Ag electrode did. Using our validated simulation, we construct an external quantum efficiency map in full ranges of the period and fill factor of the Ag-nanomesh electrode to find out the optimum nanomesh dimension.

Nanosphere Lithography: A Versatile Approach to Develop Transparent Conductive Films for Optoelectronic Applications

“…An increase of the periodicity to 2 µm reduced the charge collection efficiency, owing to increased recombination losses induced by the longer charge transport pathways to the charge collecting electrodes between the nanomesh perforations, leading to reduced J sc and FF. [171,172] In general, the diffusion length of photo-generated charge carriers inside the absorber determines the maximum feasible hole size of the nanomesh TCFs.…”

“…Corrugating the OLED device led to greatly reduced SPP losses at the metal interface (Figure 7c). [172] Compared with ITO-film based OLEDs, Ag and ITO nanomesh electrode based OLEDs have shown greatly improved current efficiency, power efficiency and EQE improvement. TCFs fabricated by NSL in OLEDs have shown great potential for high-performance device applications, aiming for commercial lighting and displays.…”

“…c) Schematic illustration of light extraction for a corrugated OLED device with an Ag nanomesh electrode. Reproduced with permission [172]. Copyright 2016, The Optical Society.…”

Aperiodic Porous Metasurface-Mediated Organic Semiconductor Fluorescence

“…Particularly, nanoporous metasurfaces have been shown to enhance the luminescence from various light-emitting materials, including organic small dye molecules, ,− organic conjugated polymers, and inorganic quantum dots or Si nanocrystals. , Ding et al reported that small-molecule OLEDs with periodic nanoporous metasurface top electrodes exhibited an external-quantum-efficiency enhancement factor of 1.57 compared to devices with an indium tin oxide electrode . Liu et al reported that conjugated polymer OLEDs with periodic nanoporous metasurface top electrodes exhibited an electroluminescence efficiency enhancement of up to 7 compared to planar metal electrodes .…”

Enhanced Light Extraction from Bottom Emission OLEDs by High Refractive Index Nanoparticle Scattering Layer

“…Other approaches have been studied to enhance the light extraction of OLEDs, adopting nano sized structures to OLEDs. By the scattering effect of the nano structures, such as gratings [19,20], metallic nanoparticles [21,22,23,24,25], and buckled substrates [24,26,27], the light trapped in glass substrate can escape. However, nano structures have limited application in OLEDs due to the complicated process, requiring high cost.…”