Influence of Capping Ligands, Solvent, and Thermal Effects on CdSe Quantum Dot Optical Properties by DFT Calculations
Fenoll, Didac A. (Universitat Autònoma de Barcelona. Departament de Química)
Sodupe Roure, Mariona (Universitat Autònoma de Barcelona. Departament de Química)
Solans Monfort, Xavier (Universitat Autònoma de Barcelona. Departament de Química)

Fecha:	2023
Resumen:	Cadmium selenide nanomaterials are very important materials in photonics, catalysis, and biomedical applications due to their optical properties that can be tuned through size, shape, and surface passivation. In this report, static and ab initio molecular dynamics density functional theory (DFT) simulations are used to characterize the effect of ligand adsorption on the electronic properties of the (110) surface of zinc blende and wurtzite CdSe and a (CdSe) nanoparticle. Adsorption energies depend on ligand surface coverage and result from a balance between chemical affinity and ligand-surface and ligand-ligand dispersive interactions. In addition, while little structural reorganization occurs upon slab formation, Cd···Cd distances become shorter and the Se-Cd-Se angles become smaller in the bare nanoparticle model. This originates mid-gap states that strongly influence the absorption optical spectra of nonpassivated (CdSe). Ligand passivation on both zinc blende and wurtzite surfaces does not induce a surface reorganization, and thus, the band gap remains nonaffected with respect to bare surfaces. In contrast, structural reconstruction is more apparent for the nanoparticle, which significantly increases its highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap upon passivation. Solvent effects decrease the band gap difference between the passivated and nonpassivated nanoparticles, the maximum of the absorption spectra being blue-shifted around 20 nm by the effect of the ligands. Overall, calculations show that flexible surface cadmium sites are responsible for the appearance of mid-gap states that are partially localized on the most reconstructed regions of the nanoparticle that can be controlled through appropriate ligand adsorption.
Ayudas:	Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1323 Agencia Estatal de Investigación PID2020-112715GB-I00 Ministerio de Ciencia e Innovación FPU18/03612
Derechos:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Publicado en:	ACS omega, Vol. 8, Num. 12 (March 2023) , p. 11467-11478, ISSN 2470-1343

DOI: 10.1021/acsomega.3c00324
PMID: 37008094

12 p, 5.5 MB

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