title: Influence of an Inorganic Interlayer on Exciton Separation in Hybrid Solar Cells.
abstract: It has been shown that in hybrid polymer-inorganic photovoltaic devices not all the photogenerated excitons dissociate at the interface immediately, but can instead exist temporarily as bound charge pairs (BCPs). Many of these BCPs do not contribute to the photocurrent, as their long lifetime as a bound species promotes various charge carrier recombination channels. Fast and efficient dissociation of BCPs is therefore considered a key challenge in improving the performance of polymer-inorganic cells. Here we investigate the influence of an inorganic energy cascading Nb2O5 interlayer on the charge carrier recombination channels in poly(3-hexylthiophene-2,5-diyl) (P3HT)-TiO2 and PbSe colloidal quantum dot-TiO2 photovoltaic devices. We demonstrate that the additional Nb2O5 film leads to a suppression of BCP formation at the heterojunction of the P3HT cells and also a reduction in the nongeminate recombination mechanisms in both types of cells. Furthermore, we provide evidence that the reduction in nongeminate recombination in the P3HT-TiO2 devices is due in part to the passivation of deep midgap trap states in the TiO2, which prevents trap-assisted Shockley-Read-Hall recombination. Consequently a significant increase in both the open-circuit voltage and the short-circuit current was achieved, in particular for P3HT-based solar cells, where the power conversion efficiency increased by 39%.
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , 27 Charles Babbage Road, CB3 0FS, Cambridge, U.K.
authors.forename: Claire L
authors.initials: CL
authors.lastname: Armstrong
authors.affiliation: Cavendish Laboratory, University of Cambridge , J.J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Price
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , 27 Charles Babbage Road, CB3 0FS, Cambridge, U.K.|Laboratoire des Matériaux et du Génie Physique, Université Grenoble-Alpes, CNRS , 3 Parvis Louis Néel, 38016 Grenoble, France.
authors.forename: David
authors.initials: D
authors.lastname: Muñoz-Rojas
authors.affiliation: Cavendish Laboratory, University of Cambridge , J.J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
authors.forename: Nathaniel J K L
authors.initials: NJ
authors.lastname: Davis
authors.affiliation: Cavendish Laboratory, University of Cambridge , J.J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Abdi-Jalebi
authors.affiliation: Cavendish Laboratory, University of Cambridge , J.J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Friend
authors.affiliation: Cavendish Laboratory, University of Cambridge , J.J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
authors.forename: Neil C
authors.initials: NC
authors.lastname: Greenham
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge , 27 Charles Babbage Road, CB3 0FS, Cambridge, U.K.
authors.forename: Judith L
authors.initials: JL
authors.lastname: MacManus-Driscoll
authors.affiliation: Cavendish Laboratory, University of Cambridge , J.J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
authors.forename: Marcus L
authors.initials: ML
authors.lastname: Böhm
authors.affiliation: Cavendish Laboratory, University of Cambridge , J.J. Thomson Avenue, Cambridge, CB3 0HE, U.K.|Department of Mechanical and Mechatronics Engineering, University of Waterloo , 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Musselman
keywords: Nb2O5; atmospheric pressure spatial atomic layer deposition; energy cascade; metal oxide; recombination; solar cell