Synthesis and optimization of MPA-capped ZnSe quantum dots for photo-activation based applications

In the present work, mercaptopropionic acid (MPA)-capped ZnSe Quantum dots (QDs) were synthesized using single-step hydrothermal treatment. HRTEM and XRD studies show that synthesized QDs are having dimension ∼2 to 3 nm. Size and fluorescence quantum yield (FQY) of the QDs were tuned by varying pH, MPA/Zn molar ratio, Se/Zn molar ratio, hydrothermal reaction time, and temperature. Fluorescence and UV–Vis absorbance spectra reveal information about optical behavior, crystallite size, and surface trap states. ZnSe QDs have a maximum FQY of 60% which may be attributed to the formation of ZnS shell over the core ZnSe. Detailed study on Urbach energies and FQY were carried out to correlate defect states of surface of ZnSe QDs and emission efficiencies of the QDs. MPA-capped ZnSe QDs in colloidal form were investigated for photo-induced fluorescence enhancement. Linear variation of fluorescence intensity upon UV radiation, promotes it as eligible material for photo-activation based applications in smaller time intervals.