Chlorine: the magic ingredient in CdTe solar cell production
The conversion efficiency of as-deposited, CdTe solar cells is poor and typically less than 5%. A CdCl2 activation treatment increases this to up to 22%. Studies have shown that stacking faults (SFs) are removed and the grain boundaries (GBs) are decorated with chlorine. Thus, SF removal and device efficiency are strongly correlated but whether this is direct or indirect has not been established. Here we explain1 the passivation responsible for the increase in efficiency but also crucially elucidate the associated SF removal mechanism. The effect of chlorine on a model system containing a SF and two GBs is investigated using density functional theory. The proposed SF removal mechanisms are feasible at the 400oC treatment temperature. It is concluded that the efficiency increase is due to electronic effects in the GBs while SF removal is a by-product of the saturation of the GB with chlorine but is a key signal that sufficient chlorine is present for passivation to occur.
[1] Hatton et al, Nature Communications, 2021, 12(1), 4938
Date: 24 February 2023, 14:00 (Friday, 6th week, Hilary 2023)
Venue: Online only | https://us02web.zoom.us/j/81261599674?pwd=dWtBNWFUVTBISlliK1JUQ3lvdE1Edz09
Speaker: Dr Pooja Goddard (Loughborough University)
Organising department: Department of Materials
Organiser: Joseph Prentice (University of Oxford)
Organiser contact email address: joseph.prentice@seh.ox.ac.uk
Part of: Oxford Advanced Materials Network
Booking required?: Not required
Audience: Members of the University only
Editor: Samantha Pearce