What are the best ligands for PbS quantum dots in solar cell applications?

[yfir]

Hi everyone,

I'm working with quantum dot (PbS). However, I'm actually not a chemist, so could anyone help me to address some issues regarding quantum dots especially related to ligand exchange process. My questions are:
1. anyone can address about what kind of functionality (e.g: thiol, acid, amine, etc) basically suitable for what nanoparticle?
2. For PbS quantum dots, could you suggest me what is the best ligand to used? especially if the quantum dot size relatively small (~2-3 nm).

thanks,
yfir

 

[chemisttree]

That would depend on what solvent you intend to use and what use you intend for the particles. Xanthates like ethyl xanthate react with the surface of PbS and dithiophosphates have been used to treat sulfide minerals in froth flotation applications.

 

[yfir]

Ah yes, Sorry, I should be more specific. The solvent used are the non-polar one such as Toluene and chlorobenzene. I will need it for solar cell application whereas normally the new ligand needed are the short one which allow efficient charge transfer and at the same time give stability of the colloidal QD. The latter one is the main problem of ligand exchange, because in most cases for small nanoparticle size, the QDs after ligand exchange tends to be aggregated. I have tried with amine and carboxylic acid ligands. However, the results haven't been satisfying. I was told that thiol ligands could be a good alternative, but I try to avoid this as most of this molecule are not really pleasant to handle. That is why I would like to know if any of you could give me at least "guidance" to choose the suitable ligand.

Thanks,
yfir