Isotype Heterojunction Solar Cells Using n-Type Sb<sub>2</sub>Se<sub>3</sub> Thin Films
Theodore D. C. Hobson, Laurie J. Phillips, Oliver S. Hutter, Huw Shiel, Jack E. N. Swallow, Christopher N. Savory, Pabitra K. Nayak, Silvia Mariotti, Bhaskar Das, Leon Bowen, Leanne A. H. Jones, Thomas J. Featherstone, Matthew J. Smiles, Mark Farnworth, Guillaume Zoppi, P. Thakur, Tien-Lin Lee, Henry J. Snaith, Chris Leighton, David O. Scanlon, V.R. Dhanak, K. Durose, T. D. Veal, Jonathan D. Major
Abstract
The carrier-type of the emerging photovoltaic Sb 2 Se 3 was evaluated for both thin films and bulk crystals via a range of complementary techniques. X-ray photoelectron spectroscopy (XPS), hot probe, Hall effect, and surface photovoltage spectroscopy showed films and crystals synthesized from the Sb 2 Se 3 granulate material to be n-type with chlorine identified as an unintentional n-type dopant via secondary ion mass spectrometry analysis. The validity of chlorine as a dopant was confirmed by the synthesis of intrinsic crystals from metallic precursors and subsequent deliberate n-type doping by the addition of MgCl 2 . Chlorine was also shown to be a substitutional n-type shallow dopant by density functional theory calculations. TiO 2 /Sb 2 Se 3 n-n isotype heterojunction solar cells with 7.3% efficiency are subsequently demonstrated, with band alignment analyzed via XPS.