Raman Spectroscopic Analysis of Cu-Ag-In-S/CdSe Core/Shell Quantum Dots Grown on Mesoporous TiO2 Substrates

Abstract

This study investigates the structural and vibrational properties of Cu-Ag-In-S/CdSe core/shell quantum dots (QDs) grown on the mesoporous TiO₂ (mp-TiO₂) substrates using Raman spectroscopy and 3D Raman mapping.  The Raman spectra revealed distinct vibrational modes of AgInS₂ and CdSe, compared to Cu-Ag-In-S, with a notable shift observed in the A₁ mode (282.2 cm^-1 to 260.8 cm^-1), E and B₂ modes (316.7 cm^-1 to 326.4 cm^-1), and an additional Cu-S mode (289.3 cm^-1 to 283.4 cm^-1). These shifts indicate significant interactions between the QDs and the substrate, as well as the presence of Cu and CdSe phases. 3D mapping provided spatial distribution data, showing enhanced Cu-incorporation and morphological variations across the substrates, with darker regions signifying Cu-enriched areas. The alterations in the Raman spectrum suggest a strong interaction between Cu-Ag-In-S and CdSe. The findings contribute to a deeper understanding of Cu-Ag-In-S/CdSe QDs, highlighting their potential to optoelectronic application.