Ultrafast transient absorption (TA) spectroscopy, a robust tool for tracking real-time charge transfer dynamics in QD-molecular systems, was used to examine the ET process in these QD-molecular complexes. Three AQ derivatives with chlorine substituents at positions 1,4,5,8 and 1,8, and 1, namely 1,4,5,8-tetrachloroanthraquinone (1,4,5,8-TTAQ), 1,8-dichloroanthraquinone (1,8-DCAQ), and 1-chloroanthraquinone (1-CAQ) respectively, were introduced as electron acceptors, and CdSe/ZnS core/shell QDs were introduced as electron donors. In this report, we studied anthraquinone (AQ) molecules with chlorine substituents. However, the role of substituents in acceptor molecules is unknown.
For the ET process, most groups have focused on changing the QDs and solvents. successfully tuned the hole transfer rate 23. By changing molecular acceptors, Alivisatos et al. Different QDs tuned by wavefunction engineering can be used to control exciton dynamics and ET properties 21, 22. Wise’s group has adjusted various solvents in PbS-10-dodecylanthracence-9-thiol (DAT) system to dramatically increase the ET rate by tuning the solvent dielectric constant 20. For instance, Lian’s group tuned the shell thickness in the CdSe/ZnS core/shell structure to slow down the ET rate by changing the radial distribution of the electron and hole wavefunctions 12. Therefore, it is important to understand the ET process, to evaluate its dependence on key factors, and promote it in a QD-based system to further advance QD-based applications. The ET process from photoexcited QDs to external acceptors through an interface 18, 19 is one of the primary mechanisms associated with the functionality and efficiency of QD devices. The electron transfer (ET) process is one of the most fundamental mechanisms in quantum dots (QDs), which are used for a wide range of nanotechnology applications such as bioimaging 1, 2, 3, 4, lasing 5, 6, 7, light-emitting diodes 8, 9, 10, molecular device operation 11, 12, 13, and solar cells 14, 15, 16, 17.
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