Strongly Confined HgTe 2D Nanoplatelets as Narrow Near-Infrared Emitters

Abstract

Two-dimensional colloidal nanoplatelets (NPLs), owing to the atomic-level control of their confined direction (i.e., no inhomogeneous broadening), have demonstrated improved photoluminescence (PL) line widths for cadmium chalcogenide-based nanocrystals. Here we use cation exchange to synthesize mercury chalcogenide NPLs. Appropriate control of reaction kinetics enables the 2D morphology of the NPLs to be maintained during the cation exchange. HgTe and HgSe NPLs have significantly improved optical features compared to existing materials with similar band gaps. The PL line width of HgTe NPLs (40 nm full width at half-maximum, centered at 880 nm) is a factor of 2 smaller than typical PbS nanocrystals (NCs) emitting at the same wavelength. The PL has a lifetime of 50 ns, almost 2 orders of magnitude shorter than small PbS colloidal quantum dots (CQDs), and a quantum yield of ∼10%, almost 2 orders of magnitude shorter than small PbS colloidal quantum dots (CQDs). These materials are promising for a large variety of applications spanning from telecommunications to the design of colloidal topological insulators.

Shape and confinement control in mid and far infrared nanocrystals

“…Due to the higher binding energy resulting from the 2D shape. The PL decay is typically 50 times faster than what can be obtained with PbS and CIGS, [5] We further investigate the transport properties of these 2D NPL. To do so, we incorporate the NPL into an electrolytic transistor, where the gate is obtained by ion gel gating [21,22].…”

“…So far, the direct synthesis of HgTe NPL has not been reported. Izquierdo et al [5] used an indirect path to obtain these NPL. They first synthetized CdTe NPL and in a second step used a cation exchange [18,19,20] procedure to remove the Cd 2+ cations from the NPL and replace them by mercury.…”

“…We present early demonstration of mid infrared optical features thanks to the growth of large and poorly confined HgTe CQD. Recently, a next step has been reached on the shape control of HgTe CQD, with the growth of HgTe 2D nanoplatelets [5]. Their anisotropic shape brings enhanced optical features with narrower and faster emission.…”

Investigation of the Self‐Doping Process in HgSe Nanocrystals

“…The growth of HgX CQD has been strongly improved over the recent years . However, to integrate this material in an infrared sensor, the doping in layers of HgS(e) must be well controlled.…”

Designing Photovoltaic Devices Using HgTe Nanocrystals for Short and Mid‐Wave Infrared Detection

“…Highly monodisperse HgTe nanocrystals can now be synthetized and present an atom‐like spectrum in the IR range . Synthetic progress also includes shape control with the synthesis of nanoplatelets and heterostructures . Another striking observation from a material point of view is the observation of self‐doping .…”