title: Partial oxidation of the absorber layer reduces charge carrier recombination in antimony sulfide solar cells.
abstract: We investigate the effect of a post heat treatment of the absorber layer in air for antimony sulfide (Sb2S3) sensitized solar cells. Phenomenologically, exposing the Sb2S3surface of sensitised solar cells to air at elevated temperatures is known to improve device performance. Here, we have investigated the detailed origins of this improvement. To this end, samples were annealed in air for different time periods and the build-up of an antimony oxide layer was monitored by XPS. A very short heat treatment resulted in an increase in power conversion efficiency from η = 1.4% to η = 2.4%, while longer annealing decreased the device performance. This improvement was linked to a reduction in charge carrier recombination at the interface of Sb2S3with the organic hole conductor, arising from the oxide barrier layer, as demonstrated by intensity modulated photovoltage spectroscopy (IMVS).
authors.affiliation: Cavendish Laboratory, Department of Physics, University of Cambridge, UK.
authors.forename: Karl C
authors.initials: KC
authors.lastname: Gödel
authors.affiliation: Adolphe Merkle Institute, Rue des Verdiers, Fribourg, Switzerland. ullrich.steiner@unifr.ch.
authors.forename: Bart
authors.initials: B
authors.lastname: Roose
authors.affiliation: Cavendish Laboratory, Department of Physics, University of Cambridge, UK.
authors.forename: Aditya
authors.identifier: http://orcid.org/0000-0003-2832-4894
authors.initials: A
authors.lastname: Sadhanala
authors.affiliation: Kirchhoff Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, Germany and Centre for Advanced Materials, Heidelberg University, Im Neuenheimer Feld 225, Germany.
authors.forename: Yana
authors.initials: Y
authors.lastname: Vaynzof
authors.affiliation: Centre for Energy Studies, Indian Institute of Technology, Delhi, India.
authors.forename: Sandeep K
authors.initials: SK
authors.lastname: Pathak
authors.affiliation: Adolphe Merkle Institute, Rue des Verdiers, Fribourg, Switzerland. ullrich.steiner@unifr.ch.
authors.forename: Ullrich
authors.identifier: http://orcid.org/0000-0001-5936-339X
authors.initials: U
authors.lastname: Steiner