I am doing some control experiments with CdSe QDs-MO2 (M=Ti or Zr) colloidal solutions. According to literature, I should see lesser quenching of emission with ZrO2 as compared to TiO2 as the band structure of QDs and ZrO2 makes it unfavorable for electron transfer from conduction band(CB) of CdSe to CB of ZrO2 (and therefore lesser quenching of emission). Whereas in case of TiO2, band structure of QD and MO2 allows electron transfer (and therefore more quenching).
When I am doing these experiments, I am getting almost 95-100% quenching with ZrO2. I am making ZrO2 NPs by adding Zirconium propoxide to ethanol. Also, by taking UV-vis of the QD-ZrO2 solution, overtime the absorbance peak of QD is blueshifting (with apparent change in color of the solution from light red to light yellow). I am unable to make any conclusions based on these observations.
I actually want to study the effect of an organic linker on quenching of emission of QD-linker-MO2 assemblies. Since, even without linker, I am getting almost 100% quenching, I am not able to proceed to use the linker with my samples.
Attached is a plot of emission intensities versus time (in mins) for my control experiments. QDs and MO2 concentrations were same for all samples.
Any suggestions are welcome.
Thanks,
Saurabh
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