title: Modulating the Electron-Hole Interaction in a Hybrid Lead Halide Perovskite with an Electric Field.
abstract: Despite rapid developments in both photovoltaic and light-emitting device performance, the understanding of the optoelectronic properties of hybrid lead halide perovskites is still incomplete. In particular, the polarizability of the material, the presence of molecular dipoles, and their influence on the dynamics of the photoexcitations remain an open issue to be clarified. Here, we investigate the effect of an applied external electric field on the photoexcited species of CH3NH3PbI3 thin films, both at room temperature and at low temperature, by monitoring the photoluminescence (PL) yield and PL decays. At room temperature we find evidence for electric-field-induced reduction of radiative bimolecular carrier recombination together with motion of charged defects that affects the nonradiative decay rate of the photoexcited species. At low temperature (190 K), we observe a field-induced enhancement of radiative free carrier recombination rates that lasts even after the removal of the field. We assign this to field-induced alignment of the molecular dipoles, which reduces the vibrational freedom of the lattice and the associated local screening and hence results in a stronger electron-hole interaction.
authors.affiliation: Center for Nano Science and Technology@Polimi, Istituto Italiano di Tecnologia , via Giovanni Pascoli 70/3, 20133 Milan, Italy.|Clarendon Laboratory, University of Oxford , Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: Tomas
authors.initials: T
authors.lastname: Leijtens
authors.affiliation: Center for Nano Science and Technology@Polimi, Istituto Italiano di Tecnologia , via Giovanni Pascoli 70/3, 20133 Milan, Italy.
authors.forename: Ajay Ram
authors.initials: AR
authors.lastname: Srimath Kandada
authors.affiliation: Clarendon Laboratory, University of Oxford , Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: Giles E
authors.initials: GE
authors.lastname: Eperon
authors.affiliation: Center for Nano Science and Technology@Polimi, Istituto Italiano di Tecnologia , via Giovanni Pascoli 70/3, 20133 Milan, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Grancini
authors.affiliation: Center for Nano Science and Technology@Polimi, Istituto Italiano di Tecnologia , via Giovanni Pascoli 70/3, 20133 Milan, Italy.|Dipartimento di Fisica, Politecnico di Milano , Piazza L. da Vinci, 32, 20133 Milan, Italy.
authors.forename: Valerio
authors.initials: V
authors.lastname: D'Innocenzo
authors.affiliation: Center for Nano Science and Technology@Polimi, Istituto Italiano di Tecnologia , via Giovanni Pascoli 70/3, 20133 Milan, Italy.
authors.forename: James M
authors.initials: JM
authors.lastname: Ball
authors.affiliation: Clarendon Laboratory, University of Oxford , Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: Samuel D
authors.initials: SD
authors.lastname: Stranks
authors.affiliation: Clarendon Laboratory, University of Oxford , Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Snaith
authors.affiliation: Center for Nano Science and Technology@Polimi, Istituto Italiano di Tecnologia , via Giovanni Pascoli 70/3, 20133 Milan, Italy.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Petrozza