title: Mechanism for Broadband White-Light Emission from Two-Dimensional (110) Hybrid Perovskites.
abstract: The recently discovered phenomenon of broadband white-light emission at room temperature in the (110) two-dimensional organic-inorganic perovskite (N-MEDA)[PbBr4] (N-MEDA = N(1)-methylethane-1,2-diammonium) is promising for applications in solid-state lighting. However, the spectral broadening mechanism and, in particular, the processes and dynamics associated with the emissive species are still unclear. Herein, we apply a suite of ultrafast spectroscopic probes to measure the primary events directly following photoexcitation, which allows us to resolve the evolution of light-induced emissive states associated with white-light emission at femtosecond resolution. Terahertz spectra show fast free carrier trapping and transient absorption spectra show the formation of self-trapped excitons on femtosecond time-scales. Emission-wavelength-dependent dynamics of the self-trapped exciton luminescence are observed, indicative of an energy distribution of photogenerated emissive states in the perovskite. Our results are consistent with photogenerated carriers self-trapped in a deformable lattice due to strong electron-phonon coupling, where permanent lattice defects and correlated self-trapped states lend further inhomogeneity to the excited-state potential energy surface.
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.|Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Te
authors.initials: T
authors.lastname: Hu
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Smith
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Emma R
authors.initials: ER
authors.lastname: Dohner
authors.affiliation: Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Meng-Ju
authors.initials: MJ
authors.lastname: Sher
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: M Tuan
authors.initials: MT
authors.lastname: Trinh
authors.affiliation: SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Alan
authors.initials: A
authors.lastname: Fisher
authors.affiliation: SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Jeff
authors.initials: J
authors.lastname: Corbett
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: X-Y
authors.initials: XY
authors.lastname: Zhu
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Hemamala I
authors.initials: HI
authors.lastname: Karunadasa
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.|Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.|PULSE Institute, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Lindenberg