CHARGE simulation: How to set bandgap grading according to the depth of a CIGS film

    • rhawns4567


      I'm a Ph.D. course at the school of electronic and electrical engineering of Kyungpook National University, Daegu, South Korea.

      I have a question about setting the CHARGE simulation material properties.

      Currently, I'm using simulation to design CIGS solar cell structures.

      CIGS material is a light-absorbing compound semiconductor.

      In addition, it has a bandgap grading with material depth.

      However, in the simulation, the bandgap of material is set to a constant.

      I wonder if it is possible to set up a simulation by applying to bandgap grading of the CIGS material as shown in the figure below.

      I will wait for your answers. Thank you.

    • Guilin Sun
      Ansys Employee
      Sorry to reply you late as our team is busy in different projects.
      As you mentioned, in CHARGE, we assume a constant bandgap. So directly using the material in the Material database cannot simulate such effect.
      There might be an alternate: since the bandgap grades with material depth, you could try to add different layers with slightly different bandgap according to the function of depth. Although in theory we can use infinitely thin layer to get smooth bandgap, for CHARGE simulation, since it uses Finite Element Method, its meshing quality may be degraded if one layer is very thin but very large in area. Otherwise the meshing mechanism will automatically try to improve the triangle or hexahedra quality, and ultimately the meshing can easily fail. That said, a staircasing bandgap could be simulated with some induced errors compared to the continuous case.

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