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Development of Efficient OLEDs from Solution Deposition
Published on: November 4, 2022
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Coherent mode coupling in highly efficient top-emitting OLEDs on periodically corrugated substrates
Optics Express
|April 11, 2014
Summary
Adding a corrugated substrate to organic light-emitting diodes (OLEDs) enhances light outcoupling. This Bragg scattering method improves external quantum efficiency (EQE) without negatively impacting electrical performance.
Area of Science:
- Optoelectronics
- Materials Science
- Photonics
Background:
- Top-emitting organic light-emitting diodes (OLEDs) utilize phosphorescent pin stacks and metal electrodes, creating microcavity effects.
- Light outcoupling efficiency is a critical parameter for OLED performance.
- Waveguided and surface plasmon modes are typically confined within the OLED stack.
Purpose of the Study:
- To investigate the use of Bragg scattering from corrugated substrates for enhancing light outcoupling in OLEDs.
- To analyze the impact of substrate corrugation on the optical and electrical properties of OLED devices.
- To understand the interference effects between scattered modes and the cavity mode.
Main Methods:
- Fabrication of OLEDs with a corrugated photoresist layer underneath the bottom electrode.
- Optical analysis of angular resolved emission spectra.
- Optical modeling to understand light scattering and interference phenomena.
Main Results:
- Corrugated substrates increase light outcoupling efficiency compared to planar structures.
- External quantum efficiency (EQE) improved from 15% to 17.5% with a 1.0 μm grating period and 70 nm modulation depth.
- Electrical properties of the OLEDs remained unaffected by the corrugation.
Conclusions:
- Bragg scattering from corrugated substrates effectively enhances light outcoupling in OLEDs.
- The observed interference between scattered modes and the cavity mode is quantitatively described.
- Substrate corrugation offers a viable method to boost OLED performance without compromising electrical characteristics.
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