jz6b00793_si_001.pdf (2.01 MB)
Mechanism for Broadband White-Light Emission from Two-Dimensional (110) Hybrid Perovskites
journal contribution
posted on 2016-06-01, 00:00 authored by Te Hu, Matthew D. Smith, Emma R. Dohner, Meng-Ju Sher, Xiaoxi Wu, M. Tuan Trinh, Alan Fisher, Jeff Corbett, X.-Y. Zhu, Hemamala I. Karunadasa, Aaron M. LindenbergThe
recently discovered phenomenon of broadband white-light emission
at room temperature in the (110) two-dimensional organic–inorganic
perovskite (N-MEDA)[PbBr4] (N-MEDA = N1-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.