How to Exploit Many-Body Interactions and Topological Phenomena in Colloidal Nanoplatelets

Juan I. Climente^a, Jordi Llusar^a, David Macías-Pinilla^b, Josep Planelles^a

^aDepartament de Química Física i Analítica, Universitat Jaume I, Av. Vicent Sos Baynat, s/n, Castellón de la Plana, Spain

^bInstitute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain

Materials for Sustainable Development Conference (MATSUS)
Proceedings of nanoGe Spring Meeting 2022 (NSM22)

#SNI22. Semiconductor Nanocrystals I: Basic Science (synthesis, spectroscopy, electronic structure, device and application)

Online, Spain, 2022 March 7th - 11th

Organizers: Emmanuel Lhuillier, Sandrine Ithurria and Angshuman Nag

Invited Speaker, Juan I. Climente, presentation 020
DOI: https://doi.org/10.29363/nanoge.nsm.2022.020
Publication date: 7th February 2022

Carriers confined in colloidal nanoplatetelets feel strong Coulomb interactions, enhanced by dielectric confinement and quasi-planar geometry. We review from a theoretical perspective how these interactions make the optoelectronic response diverge from that of quantum dots and even that of quantum wells, thus providing nanoplatelets with characteristic properties. Large exciton[1] (and trion[2]) binding energies, Giant (and Dwarf) Oscillator Strength[3] and radiative Auger processes[4] are some of the effects that can be observed with due material engineering. Special attention is paid to the role of Coulomb repulsions, which make biexcitons behave differently from simpler species, and stimulate the formation of spontaneous magnetic phases in few-electron nanoplatelets.

Further, prospects of exploiting topological effects in colloidal systems are addressed in two systems:

(i) Core/crown nanoplatelets, where carriers localized in the crown are shown to be susceptible of displaying Aharonov-Bohm phenomena;

(ii) Mercury chalcogenide nanoplatelets. Using multi-band k·p theory, we explain why recent experiments with such structures show absorption spectra which are reminiscent of cadmium-based ones, in spite of the inverted band gap these materials present in bulk. Predictions are made on the structural conditions which will permit the formation of topological (surface) states in such systems.

References:

[1] Rajadell, F.; Climente, J.I.; Planelles, J. Excitons in core-only, core-shell and core-crown CdSe nanoplatelets: Interplay between in-plane electron-hole correlation, spatial confinement, and dielectric confinement. Phys. Rev. B 2017, 96, 035307

[2] Macias-Pinilla, D.F.; Planelles, J.; Mora-Seró, I.; Climente, J.I. Comparison between Trion and Exciton Electronic Properties in CdSe and PbS Nanoplatelets, J. Phys. Chem. C 2021, 125, 15614-15622.

[3] Planelles, J.; Achtstein, A.W.; Scott, R.; Owschimikov, N.; Woggon, U.; Climente, J.I. Tuning Intraband and Interband Transition Rates via Excitonic Correlation in Low-Dimensional Semiconductors, ACS Photonics 2018, 5, 3680-3688.

[4] Llusar, J.; Climente, J.I. Nature and Control of Shakeup Processes in Colloidal Nanoplatelets. ACS Photonics 2020, 7, 3086-3095.

Acknowledgements:

Support from MICINN project CTQ2017-83781-P and Prometeo/2018/098 grant is acknowledged.

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