Poster Award on Simulating Interfaces in CdTe Thin Film Solar Cells

Aanand Thiyagarajan - the Poster Award Recipient

 

PhD student Aanand Thiyagarajan working in Dr. Sampath’s Team at the Center for Next Generation Photovoltaics, Colorado State University won the poster prize at the 46th IEEE Photovoltaic Specialists Conference (PVSC 46). Aanand was an intern at Synopsys in 2018 and has received technical and professional training from QuantumATK Team on his project with QuantumATK aiming at further improving the efficiency of CdTe solar cell devices of adsorbing and converting sunlight into electricity.

Figure 1. Aanand Thiyagarajan and his poster “Analysis of the MgxZn1-xO/CdTe interface in CdTe thin film solar cells using Density Functional Theory (DFT)”.

Aanand has used QuantumATK to model ZnO/CdTe and MgxZn1-xO (MZO)/CdTe interfaces (the front end of the device) in CdTe thin film solar cells using Density Functional Theory (DFT) and nonequilibrium Green Function (NEGF) method. Aanand used GGA DFT functional for structural relaxation of interfaces and GGA-1/2 (band gap correction) for device configurations. This work represents one of the first attempts at studying the oxide interfaces in thin film photovoltaics using the DFT+NEGF model.

 

Main results and conclusions

  • Interface strain, surface termination chemistry and geometry optimization play a crucial role in band alignment at the interface.
  • Lower strain was generally found to be favorable since it results in a higher band gap.
  • The surface termination with lower total energy has fewer interface states.
  • Structural relaxation was seen to influence band bending.
  • MZO-CdTe has better band alignment as compared to ZnO-CdTe.

 

Future work

Further computations involving CdCl2 at the interface may shed some light on the effect of the CdCl2 treatment that has been beneficial for CdTe photovoltaics.

Figure 2. Analysis of the MgxZn1-xO/CdTe interface in CdTe thin film solar cells using DFT and NEGF methods in QuantumATK.

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