Observing Charge Localization and Ligand Dynamics Through the Excited State Surface Chemistry of CdSe Quantum Dots Via Time-resolved Infrared Spectroscopy
Author | : Jianing Gan |
Publisher | : |
Total Pages | : 0 |
Release | : 2023 |
ISBN-10 | : OCLC:1424644296 |
ISBN-13 | : |
Rating | : 4/5 (96 Downloads) |
Book excerpt: The study of colloidal quantum dots (QDs) provides significant prospect for photocatalysis application. One of the unique features from colloidal QDs is tuning the interactive properties by modifying their surface. The surface ligands of QDs allow acceptor's access to QD surfaces, meanwhile protecting the core from oxidation and degradation. The combined role of ligands then provide opportunities in enhancement of photocatalysis quantum yields by positive control of ligand detachments and reattachments during the catalytic process. Based on preliminary study using time-resolved infrared (TRIR) spectroscopy to track changes of ligand bonding in the excited states of lead sulfide colloidal QDs with stearate ligands, a combination of mid-IR, visible transient absorption and PL methods were applied to the CdSe QDs, in order to probe the vibrational modes of stearate carboxyl groups attached to the surface during photoexcitation. Some unique vibrational modes from CdSe surface stearates showed interactions with surface-localized holes, and by comparing the kinetics of these hole-related vibrational features to the electronic state kinetics, it is shown that some surface-localized holes live as long as microsecond scale among the recovery of excitation states. It gave out enough time window for these holes to transfer to hole acceptors in solution. This work corresponds to previous studies on lead sulfide QDs, and provide guidance to future exploration of colloidal QD's surface chemistry with various ligands.