Proceedings of MATSUS23 & Sustainable Technology Forum València (STECH23) (MATSUS23)
DOI: https://doi.org/10.29363/nanoge.matsus.2023.084
Publication date: 22nd December 2022
Colloidal semiconductor nanocrystals are opening new routes for a wide range of optoelectronic applications, spanning from lighting to photodetection, as their electronic properties can be tuned by changing their size and shape[1]. Core-shell nanocrystals further widen the tunability of their optoelectronic properties, due to the various energy alignments between the core and shell [2].
In this contribution, we show how the interplay between density functional theory (DFT) simulations and various experimental techniques can provide fundamental insights into the atomistic and electronic structures of core-shell InAs@ZnSe semiconductor nanocrystals. In particular, we carry out a systematic comparison between various structural models simulated with DFT and the results of photoluminescence as well as x-ray diffraction and electron microscopy. This detailed comparison unveils information that is not available to either theory or experiment alone. We demonstrate that the composition of the core-shell structure does not switch abruptly between the core and the shell, but rather displays an In-Zn concentration gradient. Moreover, only by considering atomistic reconstructions on the surface of the nanocrystal as well as on the external core layer is it possible to obtain an electronic structure that matches the experimentally observed optical properties. Finally, we derived general insights to explain the observed boost in the photoluminescence quantum yield when the InAs particles are coated with the ZnSe shell.
The computing resources and the related technical support used for this work have been provided by CRESCO/ ENEAGRID High Performance Computing infrastructure and its staff [*], funded by ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development). We also acknowledge the CINECA award under the ISCRA initiative, for the availability of high-performance computing resources and support.
[*] F. Iannone et al., "CRESCO ENEA HPC clusters: a working example of a multifabric GPFS Spectrum Scale layout," 2019 International Conference on High Performance Computing & Simulation (HPCS), Dublin, Ireland, 2019, pp. 1051-1052, doi: 10.1109/HPCS48598.2019.9188135.
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