Influence of Surface Ligands on the Luminescent Properties of Cadmium Selenide Quantum Dots in a Polymethylmethacrylate Matrix

The photophysical properties of colloid semiconductor quantum dots (QDs) and QD-containing composites attract increasing interest. The possibility of tuning of the luminescence wavelength by varying the QD size, their broad absorption spectrum and feasibility of obtaining QD-based thin layers and composites offer great prospects for application in photonics and optoelectronics. Some emerging trends in the development of QD-based light-emitting diodes and solar cells require embedding of QDs into a polymer matrix. Although there is evidence that the photophysical characteristics of QDs in such systems depend on the type of their surface ligands, yet, there are only few studies on this subject. Here, the luminescence characteristics CdSe/ZnS/Cds/ZnS QDs coated with aliphatic or aromatic ligands, embedded in a polymethylmethacrylate (PMMA) matrix, have been studied. The quantum yield (QY) of the QD/PMMA composites containing QDs with aliphatic ligands has been found to be three times higher compared to those containing QDs with aromatic ligands. We assume that this effect is due to hole capture on TP aromatic π-orbital.