Defect passivation introduced through surface reconstruction in TOPO capped CdSe quantum dots for enhancement in quantum yield

Abstract In this paper we report, suppression of surface defect state emission introduced in purified CdSe quantum dots (QDs) synthesized via kinetic growth method, for enhanced photoluminescence (PL) emission. The conventional method of synthesis is modified to prepare a large amount of QDs. Through this method, four different samples of CdSe QDs of different particle sizes ranging from 3 nm to 6 nm are prepared from CdO and elemental Se and studied their optical characteristics. Particle sizes are measured from TEM images as well as DLS measurements and the functional groups attached to the QD surfaces are analyzed from FTIR spectra. The influence of surface defect on PL lifetime of the QDs is studied. The synthesized QD are purified through a process of centrifugation and decantation. The method of purification adopted is to curtail the surface defect state emissions from the QD which in turn enhances the excitonic emission. The elimination of defect emission in PL spectra is further verified in laser induced PL measurements. The quantum yields of different samples are measured and an improvement up to 9% is achieved.