Development of CZTS absorbers by sputter deposition for application in CZTS/Si tandem photovoltaics: The Copper problem

Martinho, F. M. A. (Speaker), Hajijafarassar, A. (Other), Canulescu, S. (Other), Stamate, E. (Other), Simón López Mariño (Other), Espindola Rodriguez, M. (Other), Gansukh, M. (Other), Engberg, S. L. J. (Other), Hansen, O. (Other), Andrea Crovetto (Other), Schou, J. (Other)

Activity: Talks and presentationsConference presentations

Description

Kesterite solar cells based on pure sulfide CZTS (Cu2ZnSnS4) offer prospects of a cost effective
and environmentally benign solution for photovoltaics. While promising on its own, CZTS is now
receiving increased interest for applications in monolithic CZTS/Si tandem solar cells due to its
high bandgap and low lattice mismatch with Si. However, integrating the Si and CZTS production
steps to obtain an efficient monolithic cell is a challenging task.
In this work, CZTS absorbers were produced by co- or sequential sputter deposition of the binary
precursors SnS and ZnS and of the metallic precursor Cu. The characterization of a baseline single
junction CZTS solar cell is presented, and some of the challenges and early results on the CZTS/Si
tandem cell integration are reported. CZTS was grown on a Si substrate with a TiN diffusion
barrier, to prevent the diffusion of some CZTS elements into Si during annealing – particularly Cu
and S – that can degrade the photovoltaic properties of Si. The effects of annealing on the resulting
structure were studied as a function of the initial CZTS precursor configuration and composition.
The results of this initial integration and their implications for CZTS/Si tandem devices are
discussed. The ideal thickness of the CZTS layer, in order to match the Si thickness for complete
light absorption, was studied experimentally, in conjunction with optical simulations on complete
CZTS/Si tandem structures.
Period22 Jun 2018
Held atEMRS Spring meeting 2018
Event typeConference
LocationStrasbourg, France
Degree of RecognitionInternational

Keywords

  • Solar Energy
  • solar cells
  • Photovoltaics
  • Kesterite
  • Silicon
  • Tandem cells
  • Sputtering