QuantumATK News - Poster Award on Simulating Interfaces in CdTe Thin Film Solar Cells

Figure 1. Aanand Thiyagarajan and his poster “Analysis of the Mg_xZn_1-xO/CdTe interface in CdTe thin film solar cells using Density Functional Theory (DFT)”.

Aanand has used QuantumATK to model ZnO/CdTe and Mg_xZn_1-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 Mg_xZn_1-xO/CdTe interface in CdTe thin film solar cells using DFT and NEGF methods in QuantumATK.

Relevant resources

• Step-by-step case study prepared by Synopsys QuantumATK group on the Ag-Si interface using QuantumATK. It has a similar workflow to the work done by Aanand.
• Tutorial on calculating photocurrent through a device under illumination.
• On-demand webinar on simulating interfaces and on simulating solar-cell devices including temperature effects.
• News item “New QuantumATK Study on Efficient Solar-Cell Devices Based on Stacked Janus 2D Material Layers”.
• Relevant papers: "Efficient First-Principles Calculation of Phonon-Assisted Photocurrent in Large-Scale Solar-Cell Devices", “Stacked Janus Device Concepts: Abrupt pn-Junctions and Cross-Plane Channels", “Interface bandgap narrowing behind open circuit voltage losses in Cu₂ZnSnS₄ solar cells”