Vaccum level shift / Interface charge transfer II

Introduction

In this tutorial we will simulate charge transfer at an donor-acceptor interface and calculate the resulting vacuum level shift, using input from Quantum Patch. In the simulation we will not expand the system morphology but use the orginial dimensions of the morphology generated with Deposit. The general methodology is the same as in the Tutorial Interface charge transfer I. This tutorial will in addition deal with settings specificaly needed for amorphous systems.

Input files:

  • The tutorial is based on ab-initio data generated using [Deposit] and [QuantumPatch]. You can follow the respective manuals to generate customized input, or download the QuantumPatch output here, and the pdb files to identify donor and acceptor here.
  • The settings file for command line execution can be created manually with the instructions given below or be downloaded here. If you are using SimStack insterad, the settings file will be created automatically.

Prerequisites

If you are not using SimStack to perform your computation, make sure the environment varibales neccesary to run lightforge are set as shown here.

System setup

Our system consists of an interface between an donor (molA) and an acceptor (molB) read in from Quantum Patch and an insolating charge blocking layer on both sites of the interface, as well as two short-cut electrodes. The purpose of the electrodes is to shield the electrostatic field caused by the surface dipole, charge transfer from the electrodes to the system will be deactivated. The purpose of the blocking layer is to have areas which are completly empy of charges to accuaretly determine the drop of the electrostatic potential. The system setup looks like this:

Setup and running Lightforge: Commandline and GUI(SimStack) Tutorials

You can perform this calculation by either creating a settings file manually and starting LightForge via command line, or use the SimStack GUI to setup and submit the computation.

  • The commandline tutorial can be found here.
  • The SimStack tutorial can be found here.

Inspecting the results

In case of a serial run the Vaccum level shift is printed out to the terminal (when using command line LightForge) or in the standard output file:

Corrected Vaccum level shift: -1.31 V

In case of a parallel calculation the output is printed in the files output_job_i.

Materials folder: We get a overview of the energy levels in the device in the files energy_crossection_f_x.png An estimation of the error of long range Coulomb is given in coulomb_test_i.png. The differing slope is automatically corrected in the vaccum level shift estimation. If the differnce between the lines is strong, you need to choose a finer mesh_scale. Experiments folder: The average charge distribution is shown in charge_density_average*.png The Coulomb potential (with mettalic boundary conditions) is printed in coulomb_average_i.png Potential dopants (which lightforge considers for CT), active dopants as well as electron and hole density can be inspected in dopant_density_average_i.png

The results of the search are