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.
@article{arxiv.1610.03026,
title = {Direct Patterning of Colloidal Quantum-Dot Thin Films for Enhanced and Spectrally Selective Out-Coupling of Emission},
author = {Ferry Prins and David K. Kim and Jian Cui and Eva De Leo and Kevin M. McPeak and David J. Norris},
journal= {arXiv preprint arXiv:1610.03026},
year = {2017}
}