title: Photon recycling in lead iodide perovskite solar cells.
abstract: Lead-halide perovskites have emerged as high-performance photovoltaic materials. We mapped the propagation of photogenerated luminescence and charges from a local photoexcitation spot in thin films of lead tri-iodide perovskites. We observed light emission at distances of ≥50 micrometers and found that the peak of the internal photon spectrum red-shifts from 765 to ≥800 nanometers. We used a lateral-contact solar cell with selective electron- and hole-collecting contacts and observed that charge extraction for photoexcitation >50 micrometers away from the contacts arose from repeated recycling between photons and electron-hole pairs. Thus, energy transport is not limited by diffusive charge transport but can occur over long distances through multiple absorption-diffusion-emission events. This process creates high excitation densities within the perovskite layer and allows high open-circuit voltages.
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, UK.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Pazos-Outón
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, UK.
authors.forename: Monika
authors.initials: M
authors.lastname: Szumilo
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, UK.
authors.forename: Robin
authors.initials: R
authors.lastname: Lamboll
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, UK.
authors.forename: Johannes M
authors.initials: JM
authors.lastname: Richter
authors.affiliation: Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, UK.
authors.forename: Micaela
authors.initials: M
authors.lastname: Crespo-Quesada
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, UK.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Abdi-Jalebi
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, UK.
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Beeson
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, UK.
authors.forename: Milan
authors.initials: M
authors.lastname: Vrućinić
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, UK.
authors.forename: Mejd
authors.initials: M
authors.lastname: Alsari
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, OX1 3PU Oxford, UK.
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Snaith
authors.affiliation: Center for Nanophotonics, FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, Netherlands.
authors.forename: Bruno
authors.initials: B
authors.lastname: Ehrler
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, UK. rhf10@cam.ac.uk fd297@cam.ac.uk.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Friend
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, UK. rhf10@cam.ac.uk fd297@cam.ac.uk.
authors.forename: Felix
authors.initials: F
authors.lastname: Deschler