Open AccessCorrelating ZnSe Quantum Dot Absorption with Particle Size and Concentration
Author(s) -
Reyhaneh Toufanian,
Xingjian Zhong,
Joshua Kays,
Alexander Saeboe,
Allison M. Dennis
Publication year - 2021
Publication title -
chemistry of materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.741
H-Index - 375
eISSN - 1520-5002
pISSN - 0897-4756
DOI - 10.1021/acs.chemmater.1c02501
Subject(s) - quantum dot , heterojunction , materials science , scattering , small angle x ray scattering , absorption (acoustics) , semiconductor , spectroscopy , molecular physics , transmission electron microscopy , absorption spectroscopy , analytical chemistry (journal) , chemistry , optoelectronics , optics , nanotechnology , physics , chromatography , quantum mechanics , composite material
The focus on heavy metal-free semiconductor nanocrystals has increased interest in ZnSe semiconductor quantum dots (QDs) over the past decade. Reliable and consistent incorporation of ZnSe cores into core/shell heterostructures or devices requires empirical fit equations correlating the lowest-energy electron transition (1S peak) to their size and molar extinction coefficients ( ε ). While these equations are known and heavily used for CdSe, CdTe, CdS, PbS, etc., they are not well established for ZnSe and are nonexistent for ZnSe QDs with diameters <3.5 nm. In this study, a series of ZnSe QDs with diameters ranging from 2 to 6 nm were characterized by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), UV-vis spectroscopy, and microwave plasma atomic emission spectroscopy (MP-AES). SAXS-based size analysis enabled the practical inclusion of small particles in the evaluation, and elemental analysis with MP-AES elucidates a nonstoichiometric Zn:Se ratio consistent with zinc-terminated spherical ZnSe QDs. Using these combined results, empirical fit equations correlating QD size with its lowest-energy electron transition (i.e., 1S peak position), Zn:Se ratio, and molar extinction coefficients for 1S peak, 1S integral, and high-energy wavelengths are reported. Finally, the equations are used to track the evolution of a ZnSe core reaction. These results will enable the consistent and reliable use of ZnSe core particles in complex heterostructures and devices.