Login / Signup

Chlorine activated stacking fault removal mechanism in thin film CdTe solar cells: the missing piece.

Peter HattonMichael J WattsAli AbbasJohn M WallsRoger SmithPooja Goddard
Published in: Nature communications (2021)
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 explain 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 400 ∘C 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.
Keyphrases
  • solar cells
  • drinking water
  • density functional theory
  • quantum dots
  • molecular dynamics
  • mass spectrometry
  • molecularly imprinted
  • high resolution
  • case control
  • liquid chromatography