Ultrafast Carrier Dynamics of Photo-Induced Cu-Doped CdSe Nanocrystals

The understanding of ultrafast carrier relaxation process in doped semiconductor quantum dots (QDs) is very important for their potential applications in light-emitting diodes, optoelectronics. Here, we have studied the change in electronic properties of Cu-doped CdSe QDs upon light illumination. The light-induced effect leads to the enhancement of the band edge decay time and reduces the decay time of the dopant emission due to photocorrosion of Cu-doped CdSe QDs. The bleaching recovery kinetics and the hot electron cooling dynamics have been studied by using femtosecond transient absorption spectroscopy. It is observed that the electron cooling process of doped CdSe QDs is dependent on the dopant concentration and the cooling kinetics of doped CdSe QDs are found to be slower than undoped QDs. After light irradiation, the cooling processes of hot electron and recovery process in doped systems are modified.