Use dipole source which will act as QD. The in-buit code in dipole source will calculate internal quantum efficiency (source Purcell). Additionally u can have transmission box from analysis group to cross-check quantum efficiency. 

Dear Vasanthan, thanks for your reply. I checked the dipole source as you suggested. I am still not sure how I can differentiate if I want to simulate Si QDs and CdS QDs in terms of property using this dipole source? 

I have attached a paper herewith. If you look at the figure of the abstract, I am more interested to create similar structure. Kindly let me know what do you think about it.

Thanks in advance

You can create core-shell configuration by embedding sphere inside sphere and defining material properties respectively for core and shell. At center of core, you can define dipole source which will act as QD. 

For more information please refer the following link:

https://kx.lumerical.com/t/simulating-hollow-objects-or-coated-objects-using-mesh-order/425

Dear Vasanthan, thanks for your reply. I think the solution you suggested will work in this case. I will definitely try this one. I might get back to you later if I have any queries. Thanks a lot again. :) 

Thanks for both of you, dear researchers. I want to know could I solve Schrodinger equation for such simulated QD and obtain eigenstates and eigen energies.

Thanks for your help.

Afshin Gholizadeh That would be a different story. You need something other than Lumerical FDTD, which is the main topic in this question.