In order to insert quantum dots between two layers in ATLAS device simulator (Silvaco TCAD) deckbuild, you may have several choices. Please refer to this paper which is about quantum dot organic light emitting diode simulation via TCAD:
Article Simulation of a new architecture of organic white-light-emit...
Also, please refer to the attached SILVACO code with .in extension file aims to model quantum dots with different size in organic light emitting diode (OLED) so that we get a chance to have white light organic light emitting diode. Moreover, there is an opportunity to modify the codes according to your case study.
I hope the simulation code could come in handy for your case study.
In order to have valid simulation and reach an agreement between our simulation results with those reported in this paper:
Article Simulation of a new architecture of organic white-light-emit...
Please study the whole paper in detail then refer to the attached video, OLED simulation codes including (quantum dot OLED with photonic crystal structure and conventional structure) running in deckbuild environment (SILVACO ATLAS).
Regarding your question, I am wondering what your SILVACO software version is?
Do you have Linux based SILVACO software or not?
The issue may stem from syntax error and your software version.
I am not sure but sometimes some software version commands may differ from the others in syntax, etc!