Defect rich seed mediated growth: a novel synthesis method to enhance defect emission in nanocrystals

In the present work, we show the synthesis of defect rich ZnO quantum dots (QDs) of different sizes by considering both thermodynamic and kinetic principles. Initially, defect rich smaller size ZnO QDs are prepared by spontaneous nucleation and crystallization of ZnO under different dielectric heating rates. We observed an enhanced defect emission in ZnO QDs synthesized at rapid heating rate when compared with ZnO QDs synthesized at slow heating rate. This implies a thermodynamic incorporation of high density of defects in ZnO QDs. These QDs are then used as a seed for the growth of different sized defect rich ZnO QDs. The photoluminescence study confirms that the QDs grown from defect rich seeds show increased defect emission in comparison with QDs grown from seeds with fewer defects. All the different sized QDs grown from defect rich seeds exhibit high quantum yield, good stability, monodispersity and possess size tunable defect emission. The demonstrated synthesis approach is a promising strategy to enhance defect emission in nanocrystals.