Dear Blagojevic

Please read the Chapter 3, 4 and 5 of "Organic and Inorganic Nanomaterials".

Could you be more specific please (publisher, year, link,...) ?

Dear

pls fiend the attached file

Thank you for the book. This is more general information, I had a more specific type of system in mind. I have been doing some calculations on these systems. Quantum dot cluster (QD) is Cd15Se15 and 2 or 3 of these are conjugated using molecular linkers. Kohn-Sham HOMO-LUMO-gap for the system changes depending on the size of the system (number of QDs and linker molecules) and coupling between the individual QDs, depending on the type of linker used.

Linker 1 has a C=C bond in the middle, while linker2 replaces CH=CH group with benzene ring. This changes the system dramatically. Linker1 gives rise to hopping conductivity (at least as far as I can see), while linker2 creates strongly coupled QD system.

The values of K-S H-L gap are as follows:

Cd15Se15 (QD)  2.91eV

QD-linker1-QD      2.68eV

QD=two linker1s=QD 2.65eV

QD-linker1-QD-linker1-QD  2.64eV

QD-linker2-QD 1.38eV

QD=two linker2s=QD 1.25eV

QD-linker2-QD-linker2-QD 1.05eV

K-S gap remains relatively constant for linker1 and decreases continuously for linker2. I think this demonstrates weak and strong QD coupling through molecular linker. In that context, I was wondering if anyone had any experience with these types of systems. I haven't found much literature on this. Most of the research in literature was done on systems with hopping conductivity or attaching QDs to polymer chain. I haven't seen any work done on creating hybrid polymeric materials with QD incorporated as a link in the polymer chain.

Intersting Sr. Blagojevis.

you already calculates the band gap variation using bifuctional linker more often used in these sistem like HS-R-COO

I think more difficult linked the QDs with only the Carbon without other group with more affinity for the QDs.

The link to QD was established using amino group. It is just that the change in behavior was observed when the part of the linker not connected to QD was changed.

Interesting idea, but is it possible in experiment? The behavior you are observing is similar to the results from the prior works on the usage of various functional groups as a passivating layer. Have you looked at this aspect?

Iam working with TiO2 sentitized with CdS QDs for photocatalysis.. I used linker mercaptopropionic acid (MPA). the CdS absorbs visible ligth and transfer the electron to TiO2 will be used for photocatalytic REDOX reaction. I think this system its some kind of coupled system..This electron transfer will be depend of the linker used.

RE: Johan Rene Gonzalez

Yes, that is a coupled system. Transfer of electron from QD to TiO2 means that this is a coupled system. However, a limitation of this (and most other DSSC type systems) is that QDs are in a monolayer on the surface. I would like to create a coupled system that would allow multilayer system that would efficiently transfer electrons to the electrode (TiO2 or other). I think that the calculations I have suggest coupling in the system, chemically speaking these QDs should create a hybrid polymer. I am not sure, though, whether strong coupling between QDs or some kind of hopping conductivity would give best results, so I am looking at them both.

RE: Mahesh Neupane

Experimentally, I think it should be possible. I did some preliminary experiments where I capped CdSe QDs and achieved extinction of photoluminescence and a red shift in the absorption spectrum of QD. I have also done chemical reaction on these capped QDs that is equivalent to the reaction required to form linkers like the ones I am studying right now. I don't know how this linking would turn out in the actual system: would it create QD conglomerates, or a real polymer; how stable would the system be mechanically and chemically (resistance to oxidation in air, for instance). So, with a few caveats, I believe it should work in the experiment and that it should replicate the behavior from DFT calculations.