Abstract
Semiconductor quantum dots (QDs) have aroused great fundamental and technological interest due to their novel size-tunable optical properties, and the resulting potential applications in photonics, photoelectronics and biomedicine. In this study, uniform, ultrasmall, well-defined CdS@CdSe core-shell QDs are successfully synthesized by a hot injection method for ultrafast carrier dynamics activities. Femtosecond transient absorption studies show that the bleach recovery time of the CdS@CdSe QDs increases with the thickness of the CdSe shell. In addition, theoretical calculations were carried out to reveal this characteristic. The slower carrier relaxation of the CdS@CdSe QDs indicates its great potential applications from light-emitting diodes to photodetectors and photovoltaics. In short, this work provides a valuable reference platform for the application of core-shell QD-based heterostructure in optics and optoelectronics.
•CdS@CdSe core-shell quantum dots were synthesized by hot injection method.•CdS@CdSe core-shell quantum dots have been demonstrated to have slower bleach recovery time than the original sample.•Theoretical calculations were carried out to reveal the photogenerated carriers in CdS@CdSe core-shell quantum dots.