title: Direct Patterning of Colloidal Quantum-Dot Thin Films for Enhanced and Spectrally Selective Out-Coupling of Emission.
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 bull's-eye gratings we can produce strong directional beaming (10° divergence) with up to 6-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 μJ/cm2. In addition, we demonstrate that these structures can be fabricated on flexible substrates. Finally, 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 toward significantly improved optical properties of colloidal quantum-dot assemblies.
authors.affiliation: Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich , 8092 Zurich, Switzerland.
authors.forename: Ferry
authors.identifier: 0000-0001-7605-1566
authors.initials: F
authors.lastname: Prins
authors.affiliation: Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich , 8092 Zurich, Switzerland.
authors.forename: David K
authors.initials: DK
authors.lastname: Kim
authors.affiliation: Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich , 8092 Zurich, Switzerland.
authors.forename: Jian
authors.initials: J
authors.lastname: Cui
authors.affiliation: Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich , 8092 Zurich, Switzerland.
authors.forename: Eva
authors.initials: E
authors.lastname: De Leo
authors.affiliation: Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich , 8092 Zurich, Switzerland.
authors.forename: Leo L
authors.initials: LL
authors.lastname: Spiegel
authors.affiliation: Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich , 8092 Zurich, Switzerland.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: McPeak
authors.affiliation: Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich , 8092 Zurich, Switzerland.
authors.forename: David J
authors.initials: DJ
authors.lastname: Norris
keywords: Quantum dot; lasing; photonics; template stripping