Direct Patterning of Colloidal Quantum-Dot Thin Films for Enhanced and Spectrally Selective Out-Coupling of Emission

TL;DR

This paper introduces a surface patterning technique for colloidal quantum-dot films that enhances emission directionality, increases out-coupling efficiency, and enables spectrally selective light emission, advancing optoelectronic device performance.

Contribution

It presents a novel template-stripping method for direct patterning of quantum-dot films, achieving high-resolution structures with improved optical properties and lasing capabilities.

Findings

Achieved six-fold enhancement of spontaneous emission out-coupling.

Observed narrow single-mode lasing at low thresholds.

Demonstrated spectrally selective out-coupling using size-tunable quantum dots.

Abstract

We report on a template-stripping method for the direct surface patterning of colloidal quantum-dot thin films to produce highly luminescent structures with feature sizes less than 100 nm. Through the careful design of high quality bulls-eye gratings we can produce strong directional beaming (10{\deg} divergence) with up to six-fold out-coupling enhancement of spontaneous emission in the surface-normal direction. A transition to narrow single-mode lasing is observed in these same structures at thresholds as low as 120 {\mu}J/cm2. Furthermore, making use of the size-tunable character of colloidal quantum dots, we demonstrate spectrally selective out-coupling of light from mixed quantum-dot films. Our results provide a straightforward route towards significantly improved optical properties of colloidal quantum-dot assemblies.