Meet our two interns, PhD students Anthony Nicholson and Aanand Thiyagarajan, from Colorado State University, who are working on the next generation CdTe based solar cell devices for sustainable energy generation which is economically competitive with fossil fuel. CdTe based solar cell device technology is used by First Solar, Inc. and other manufacturers of solar cells. Their internships are funded by National Science Foundation in the USA.
Simulating intefaces in solar cell devices
Anthony and Aanand receive technical and professional training from Synopsys QuantumWise on their projects aiming at further improving the efficiency of CdTe solar cell devices of adsorbing and converting sunlight into electricity (the current efficiency is 19.16%, 2017). In particular, Anthony is using QuantumATK (former VNL-ATK) to simulate CdTe/Te interfaces (the back end of the device shown in the Figure below) whereas Aanand is modeling MgZnO(MZO)/CdTe interfaces (the front end of the device shown in the Figure below). They are investigating the electronic properties with respect to interface strain, structural orientation at the interface, and doping concentration.
Interface strain along with varied CdTe orientation at the CdTe/Te interface create band gap states within the Te layer. Overall, the CdTe(111) orientation creates a better interface with the Te Back contact. Further investigation with varied p-type doping concentration of the Te layer will be made to understand its effect on the electronic properties at the CdTe/Te interface.
Have a look at the step-by-step case study prepared by Synopsys QuantumWise on the Ag-Si interface using QuantumATK. It has a similar workflow as the work done by Anthony and Aanand. The atomic-scale modelling tools in QuantumATK are designed to study metal-semiconductor interfaces, because they describe the interface using the physically correct boundary conditions, and account correctly for the semiconductor band gap and doping.