TY - JOUR
T1 - Two-Dimensional CdSe-PbSe Heterostructures and PbSe Nanoplatelets
T2 - Formation, Atomic Structure, and Optical Properties
AU - Salzmann, Bastiaan B.V.
AU - Wit, Jur de
AU - Li, Chen
AU - Arenas-Esteban, Daniel
AU - Bals, Sara
AU - Meijerink, Andries
AU - Vanmaekelbergh, Daniel
N1 - Funding Information:
H. Meeldijk is kindly acknowledged for helping with electron microscopy at Utrecht University. T. Prins is kindly acknowledged for useful discussions. B.B.V.S. and D.V. acknowledge the Dutch NWO for financial support via the TOP-ECHO Grant No. 715.016.002. D.V. acknowledges financial support from the European ERC Council, ERC Advanced Grant 692691 “First Step”. J.W. and A.M. acknowledge financial support from the project CHEMIE.PGT.2019.004 of TKI/Topsector Chemie, which is partly financed by the Dutch NWO. S.B, C.L., and D.A.E. acknowledge financial support from the European ERC Council, ERC Consolidator Grant No. 815128. This project has received funding from the European Union’s Horizon 2020 research and innovation program under Grant No. 731019 (EUSMI).
Publisher Copyright:
© 2022 The Authors. Published by American Chemical Society
PY - 2022/1/17
Y1 - 2022/1/17
N2 - Cation exchange enables the preparation of nanocrystals (NCs), which are not reachable by direct synthesis methods. In this work, we applied Pb2+-for-Cd2+ cation exchange on CdSe nanoplatelets (NPLs) to prepare two-dimensional CdSe-PbSe heterostructures and PbSe NPLs. Lowering the reaction temperature slowed down the rate of cation exchange, making it possible to characterize the intermediary NCs ex situ with atomically resolved high-angle annular dark-field scanning transmission electron microscopy and optical spectroscopy. We observe that the Pb2+-for-Cd2+ cation exchange starts from the vertices of the NPLs and grows into the zinc blende CdSe (zb-CdSe) lattice as a rock salt PbSe phase (rs-PbSe), while the anion (selenium) sublattice is being preserved. In agreement with previous works on CdTe-PbTe films, the interfaces between zb-CdSe and rs-PbSe consist of shared {001} and {011} planes. The final PbSe NPLs are highly crystalline and contain protrusions at the edges, which are slightly rotated, indicating an atomic reconfiguration of material. The growth of PbSe domains into CdSe NPLs could also be monitored by the emission peak shift as a function of the exchange time. Temperature-dependent emission measurements confirm a size-dependent change of the band gap energy with temperature and reveal a strong influence of the anisotropic shape. Time-resolved photoluminescence measurements between 4 and 30 K show a dark-bright exciton-state splitting different from PbSe QDs with three-dimensional quantum confinement.
AB - Cation exchange enables the preparation of nanocrystals (NCs), which are not reachable by direct synthesis methods. In this work, we applied Pb2+-for-Cd2+ cation exchange on CdSe nanoplatelets (NPLs) to prepare two-dimensional CdSe-PbSe heterostructures and PbSe NPLs. Lowering the reaction temperature slowed down the rate of cation exchange, making it possible to characterize the intermediary NCs ex situ with atomically resolved high-angle annular dark-field scanning transmission electron microscopy and optical spectroscopy. We observe that the Pb2+-for-Cd2+ cation exchange starts from the vertices of the NPLs and grows into the zinc blende CdSe (zb-CdSe) lattice as a rock salt PbSe phase (rs-PbSe), while the anion (selenium) sublattice is being preserved. In agreement with previous works on CdTe-PbTe films, the interfaces between zb-CdSe and rs-PbSe consist of shared {001} and {011} planes. The final PbSe NPLs are highly crystalline and contain protrusions at the edges, which are slightly rotated, indicating an atomic reconfiguration of material. The growth of PbSe domains into CdSe NPLs could also be monitored by the emission peak shift as a function of the exchange time. Temperature-dependent emission measurements confirm a size-dependent change of the band gap energy with temperature and reveal a strong influence of the anisotropic shape. Time-resolved photoluminescence measurements between 4 and 30 K show a dark-bright exciton-state splitting different from PbSe QDs with three-dimensional quantum confinement.
UR - http://www.scopus.com/inward/record.url?scp=85123352205&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcc.1c09412
DO - 10.1021/acs.jpcc.1c09412
M3 - Article
AN - SCOPUS:85123352205
SN - 1932-7447
VL - 126
SP - 1513
EP - 1522
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 3
ER -