Effect of ZnSe and CdS Shells on the Structural and Photophysical Behavior of CdSe Nanocrystals in a PVA Matrix

The CdSe nanocrystals implanted in a polyvinyl alcohol (PVA) matrix are examined in this work to determine the influence of ZnSe and CdS shells on their structural and photophysical behavior. By using a controlled experimental methodology, we were able to synthesis four different sets of samples using the same base conditions and systematically varying just the shell composition. There were a total of 125 samples distributed throughout the categories, which comprised bare CdSe cores, CdSe/ZnSe single-shell, CdSe/CdS single-shell, and CdSe/ZnSe/CdS double-shell nanocrystals. The structural investigation, which included TEM and XRD, verified that the particle size and crystallite domains increased gradually during shelling, and that lattice strain decreased, suggesting an improvement in crystal quality. Quantum yield rose dramatically from bare CdSe to double-shelled samples, and optical measurements showed that absorption and emission peaks shifted red as the photoluminescence full width at half maximum (FWHM) shrank. The results of the time-resolved PL analysis demonstrated that the improved surface passivation led to longer lifetimes and the suppression of non-radiative decay channels. Shelling also significantly enhanced PVA's photostability, thermal resistance, film smoothness, and environmental robustness, according to stability evaluations. In addition to improving the structural integrity and environmental stability of CdSe nanocrystals, our results show that ZnSe and CdS shells increase luminescence efficiency, suggesting that these materials might be used in optoelectronic and photonic applications