Size‐dependent Auger recombination in CdSe quantum dots studied by transient absorption spectroscopy

Abstract As closely related to exciton quenching, Auger recombination (AR) is very important to colloidal semiconductor quantum dots (QDs) in applications such as lasing, solar energy conversion, and light‐emitting diodes. It is beneficial to understand the kinetic mechanism of AR. In this article, colloidal CdSe QDs with a narrow range of diameters, 2.7, 2.5, 2.3, 2.2, and 2.0 nm, are synthesized by adequately modulating the reaction temperature and time during hot injection synthesis. With sizes less than the Bohr exciton radius, the resultant collision probability differs for various CdSe QDs attributed to the varying extent of the spatial confinement effect. To analyze the bi‐exciton AR in these QDs, the ultrafast time‐resolved absorption spectrum is utilized to derive the bi‐exciton lifetime ( τ BX ) in high precision as a function of QD size. The τ BX varying with volume ( V ) obeys the universal scaling law; that is, τ BX = γV . In our experiments, the scaling factor γ is 1.649 ± 0.097 ps/nm 3 . This study could provide further insight for understanding the theory of the AR process and rational design of optoelectronic devices based on colloidal QDs.