표면 플라즈몬 주파수 변환층을 이용한 실버-유전체 투명전극과 이를 이용한 고효율 광전자 소자에 관한 연구

Abstract

Transparent electrodes to enhance external quantum efficiency (EQE) in optoelectronic devices are proposed based on the suppression of surface plasmons (SPs) at the metal–dielectric (or metal–organic) interface using a frequency conversion layer. Plasmonic ab-sorption at Ag-based electrodes causes severe optical losses in the planar stacks of optoe-lectronic devices. Even though Ag is suitable for transparent electrodes owing to its lowest absorption coefficient compared to other metals, the surface plasmon resonant frequency (SPRF) of Ag is located in the visible region (i.e., ωSP ~ 3.9 eV, λSP = 500 ~ 550 nm). Thus, incident light is absorbed by surface plasmon resonance (SPR) at the interface be-tween Ag and dielectric materials. These plasmonic resonances could be dramatically sup-pressed by adding a 2 nm-thick Al interlayer with resonance frequency out of the visible region (i.e., ωSP ~ 15 eV, λSP = 250 ~ 300 nm), which results in an extreme enhancement of the optical transmittance of Ag-based electrodes from 68% to 91% at 470 nm. These approaches for highly transparent and conductive multilayer stacks are applicable to uni-versal optoelectronics because they are straightforward, cost-effective and reliable even in large area fabrication.