nl0c02153_si_002.avi (23.53 MB)
Thickness-Tunable Self-Assembled Colloidal Nanoplatelet Films Enable Ultrathin Optical Gain Media
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posted on 2020-08-06, 22:01 authored by Onur Erdem, Sina Foroutan, Negar Gheshlaghi, Burak Guzelturk, Yemliha Altintas, Hilmi Volkan DemirWe
propose and demonstrate construction of highly uniform, multilayered
superstructures of CdSe/CdZnS core/shell colloidal nanoplatelets (NPLs)
using liquid interface self-assembly. These NPLs are sequentially
deposited onto a solid substrate into slabs having monolayer-precise
thickness across tens of cm2 areas. Because of near-unity
surface coverage and excellent uniformity, amplified spontaneous emission
(ASE) is observed from an uncharacteristically thin film having 6
NPL layers, corresponding to a mere 42 nm thickness. Furthermore,
systematic studies on optical gain of these NPL superstructures having
thicknesses ranging from 6 to 15 layers revealed the gradual reduction
in gain threshold with increasing number of layers, along with a continuous
spectral shift of the ASE peak (∼18 nm). These observations
can be explained by the change in the optical mode confinement factor
with the NPL waveguide thickness and propagation wavelength. This
bottom-up construction technique for thickness-tunable, three-dimensional
NPL superstructures can be used for large-area device fabrication.