Physics and Astrophysics Research Seminar Series

Improving CdTe Photovoltaic Efficiency: An Atomistic Modelling Viewpoint

A picture of atoms
Seminars

As part of the School of Science and Technology's Physics and Astrophysics Research Seminar Series, Michael Watts, Loughborough University presents: Improving CdTe Photovoltaic Efficiency: An Atomistic Modelling Viewpoint.

  • From: Wednesday 22 January 2020, 1 pm
  • To: Wednesday 22 January 2020, 2 pm
  • Location: 015, CELS, Nottingham Trent University, Clifton Campus, Clifton Lane, Nottingham, NG11 8NS
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Event details

As part of the School of Science and Technology's Physics and Astrophysics Research Seminar Series, Michael Watts, Loughborough University presents: Improving CdTe Photovoltaic Efficiency: An Atomistic Modelling Viewpoint.

Abstract

Cadmium Telluride is the dominant thin-film solar technology, offering a number of advantages over the more familiar Si-based modules. However the complex cell structure and material properties produce a large number of atomic defects which lead to poor efficiency. As deposited, a CdTe solar cell is <1% efficient. A so-called 'activation treatment' with CdCl2 is required to increase this efficiency up to ~14%. While this treatment has been used for decades the precise mechanism of this remarkable improvement is poorly understood. From experimental observations it is known that chlorine strongly segregates to grain boundaries and removes the very high density of stacking faults in the material. Separating the effects of these two phenomena is not possible by experimental means.

State of the art computer simulations using Density Functional Theory have therefore been used to probe the structural and electronic impact of chlorine within CdTe to further understand the improvement mechanism and find any potential improvements.

Stacking faults are shown to have little effect on cell performance while Cl at grain boundaries passivates defects, reducing harmful recombination and improving cell efficiency. A novel mechanism of stacking fault removal by Cl acting at grain boundaries is proposed, linking the two experimental observations for the first time. Other elements are tested to help understand the underlying chemistry/physics of these effects.

Beyond the activation treatment, alloying Se into CdTe has recently taken the record efficiency up to 22.1%. Simulations of this CdSexTe1-x alloy show that while Se on it's own does have some beneficial effects there is likely to be a more complex improvement mechanism occurring in grain interiors, laying the foundation for further simulations in this fast-moving area of research.

This seminar is hosted by James Rawlings & Ian Shuttleworth

All Welcome

For any enquires please contact Ian Shuttleworth

Location details

Room/Building:

015, CELS

Address:

Nottingham Trent University
Clifton Campus
Clifton Lane
Nottingham
NG11 8NS

Past event

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