Coupled electronic states in CdTe quantum dot assemblies fabricated by utilizing chemical bonding between ligands

Semiconductor quantum dot superlattices (QDSLs) have attracted much attention as key materials for realizing new optoelectronic devices such as solar cells with high conversion efficiency and thermoelectric elements with high electrical conductivity. To improve the charge transport properties of QDS...

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Published inNanoscale Vol. 12; no. 13; pp. 7124 - 7133
Main Authors Lee, Yong-Shin, Ito, Tatsuya, Shimura, Kunio, Watanabe, Taichi, Bu, Hang-Beom, Hyeon-Deuk, Kim, Kim, DaeGwi
Format Journal Article
LanguageEnglish
Published England Royal Society of Chemistry 07.04.2020
Subjects
Absorption spectra
Assemblies
Cadmium tellurides
Charge transport
Chemical bonds
Dependence
Electrical resistivity
Electron states
Excitation spectra
Ligands
Optoelectronic devices
Photoluminescence
Photovoltaic cells
Quantum dots
Solar cells
Superlattices
Transport properties
Wave functions
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Summary:Semiconductor quantum dot superlattices (QDSLs) have attracted much attention as key materials for realizing new optoelectronic devices such as solar cells with high conversion efficiency and thermoelectric elements with high electrical conductivity. To improve the charge transport properties of QDSL-based optoelectronic devices, it is important that the QD structures form minibands, which are the coupled electronic states between QDs. A shorter inter-QD distance and a periodic arrangement of QDs are the essential conditions for the formation of minibands. In this study, we use CdTe QDs capped with short ligands of N -acetyl- l cysteine (NAC) to fabricate three-dimensional QD assemblies by utilizing chemical bonding between NACs. Absorption spectra clearly display the quantum resonance phenomenon originating from the coupling of the wave functions between the adjacent QDs in CdTe QD assemblies. Furthermore, we demonstrate the formation of minibands in CdTe QD assemblies by examining both, the excitation energy dependence of photoluminescence (PL) spectra and the detection energy dependence of PL excitation spectra. The fabrication method of QD assemblies utilizing chemical bonding between NACs can be applied to all QDs capped with NAC as a ligand. The formation of coupled electronic states (minibands) is demonstrated in CdTe QD assemblies fabricated by utilizing chemical bonding between ligands.
Bibliography:Electronic supplementary information (ESI) available: Experimental data on size-selective PL spectra. See DOI
10.1039/d0nr00194e
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ISSN:2040-3364
2040-3372
DOI:10.1039/d0nr00194e