Ultrafast Charge Carrier Delocalization in CdSe/CdS Quasi-Type II and CdS/CdSe Inverted Type I Core–Shell: A Structural Analysis through Carrier-Quenching Study

• DOI: 10.1021/acs.jpcc.5b08913
• Publication Date: 2015-10-27T16:33:24Z
• Authors: Partha Maity; Tushar Debnath; Hirendra N. Ghosh
• Keywords: Charge carrier; Trion

We have employed femtosecond transient absorption spectrocopy to monitor charge carrier delocalization in CdSe/CdS quasi-type II and CdS/CdSe inverted type I core–shell nanocrystals (NCs). Interestingly, CdSe CdS QD pairs can make both structures, depending on their band alignment localization. Steady-state optical luminescence studies show a gradual red-shift emission spectra with increasing shell thickness. The quantum yield drastically increases Notably, shows huge which closely matches the edge photoluminescence (PL) of pure QDs (shell). However, does not change much Depending energy level alignment, (electron hole) core–shells been demonstrated using electron (benzoquinone, BQ) hole (pyridine, Py) quencher. bleach recovery kinetics recovers faster presence BQ Py. for core–shell, only while dynamics remain unaffected Our experimental observations suggest that photoexcited electrons are localized holes core; however, shell.