title: Spatial and temporal imaging of long-range charge transport in perovskite thin films by ultrafast microscopy.
abstract: Charge carrier diffusion coefficient and length are important physical parameters for semiconducting materials. Long-range carrier diffusion in perovskite thin films has led to remarkable solar cell efficiencies; however, spatial and temporal mechanisms of charge transport remain unclear. Here we present a direct measurement of carrier transport in space and in time by mapping carrier density with simultaneous ultrafast time resolution and ∼50-nm spatial precision in perovskite thin films using transient absorption microscopy. These results directly visualize long-range carrier transport of ∼220 nm in 2 ns for solution-processed polycrystalline CH3NH3PbI3 thin films. Variations of the carrier diffusion coefficient at the μm length scale have been observed with values ranging between 0.05 and 0.08 cm(2) s(-1). The spatially and temporally resolved measurements reported here underscore the importance of the local morphology and establish an important first step towards discerning the underlying transport properties of perovskite materials.
authors.affiliation: Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Guo
authors.affiliation: 1] Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA [2] Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Manser
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wan
authors.affiliation: 1] Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA [2] Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA [3] Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Prashant V
authors.initials: PV
authors.lastname: Kamat
authors.affiliation: 1] Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA [2] Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Libai
authors.initials: L
authors.lastname: Huang