Over 100% Light Extraction Enhancement of Organic Light Emitting Diodes Using Flat Moire Micro-Lens Array Fabricated by Double Nanoimprint Lithography Over a Large Area

TL;DR

This paper presents a novel large-area flat Moire micro-lens array fabricated by double nanoimprint lithography that doubles the light extraction efficiency of OLEDs, significantly improving their performance.

Contribution

The study introduces a new metamaterial-based flat Moire micro-lens array fabricated via scalable nanoimprint lithography, achieving over 100% light extraction enhancement in OLEDs.

Findings

Over 100% increase in light extraction efficiency

Successful large-area fabrication on 4-inch wafers

Enhanced OLED performance with the new lens array

Abstract

To improve the light extraction efficiency of organic light emitting diodes (OLEDs), we developed a novel substrate, i.e., a metamaterial based flat Moire micro-lens array formed using double nanoimprint, termed Mlens-array, consisting of a hexagonal moir\'e pattern pillar array. By choosing a low refractive index dielectric material for the pillar array and a high refractive index dielectric material for the layer capped on top of the pillar array, we fabricated the Mlens-array behaving as a conventional convex optical micro-lens array. The Mlens-array was fabricated on a 4-inch wafer-size glass substrate by double-cycle compositional nanoimprint lithography (NIL) which is easy for achieving high throughput fabrication in large-scale. Applying the Mlens-array substrate in a typical green-emitting OLED, the light extraction efficiency was enhanced by over 100% (2.08-fold) compared to a control device fabricated on the conventional planar glass substrate.