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SUMMARY:From Visible to Infrared Emitters 2D Nanoplatelets - Professor San
 drine Lhuillier-Ithurria\, ESPCI
DTSTART:20160621T133000Z
DTEND:20160621T143000Z
UID:TALK66075@talks.cam.ac.uk
CONTACT:Stuart Higgins
DESCRIPTION:2D colloidal nanoparticles\, called nanoplatelets\, have attra
 cted attention in the last couple years. Cadmium chalcogenides nanoplatele
 ts exhibit improved optical features such as narrow photoluminescence line
 width thanks to the atomic control of their confinement direction (i.e. no
  inhomogeneous broardening). All the three cadmium chalcogenides have been
  synthesized with a zinc blende structure and at least three different thi
 cknesses from 2 to 4 monolayers. It is then possible to tune their emissio
 n properties either by growing core/crown heterostructures (lateral growth
 )\, or core/shell heterostructures (thickness growth). In core/crown nanop
 latelets\, a type I band alignement obtain for CdSe/CdS leads to an increa
 se of the emission quantum yield. While in type II CdSe/CdTe we observe a 
 broad emission in the near infrared (NIR) with a large Stoke shift compare
  to the absorption. It is now possible to obtain NPLs which absorbs and em
 its in the NIR. In order to reach this region\, we use cation exchange on 
 cadmium chalcogenides NPLs. Indeed\, cation exchange is a way to reach com
 positions of nanoplatelets which cannot be directly synthesized. Thus HgTe
  and HgSe nanoplatelets have been obtained. HgTe NPLs present emission fea
 tures in the near infrared range with a full width at half maximum at leas
 t two times thinner than the classical emitters in that range. In addition
  their photoluminescence lifetime is of 55ns for a quantum yield of 10%. T
 hese new materials are promising for a large variety of applications spann
 ing from photovoltaic to the design of colloidal topological insulators.
LOCATION:Kapitza Building Seminar Room\, Cavendish Laboratory\, Department
  of Physics
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