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Long-Lived Hot Carriers in Formamidinium Lead Iodide Nanocrystals
journal contribution
posted on 2017-05-15, 00:00 authored by Paris Papagiorgis, Loredana Protesescu, Maksym V. Kovalenko, Andreas Othonos, Grigorios ItskosThe efficient harvesting
of hot carrier energy in semiconductors
is typically inhibited by their ultrafast thermalization process.
Recently, highly promising experiments reported on the slowdown of
the intraband relaxation in hybrid metal halide perovskites. In this
work, we report on the presence of long-lived hot carriers in weakly
confined colloidal nanocrystals (NCs) of formamidinium lead iodide
perovskite (FAPbI3). The effect is apparent from the excitation-dependent
lengthening of the rise time and broadening of the high-energy tail
of the transient absorption bleaching signal, yielding a retardation
of the carrier relaxation by 2 orders of magnitude compared to typical
time scales in colloidal semiconductor NCs. Three distinct cooling
stages are observed, occurring at sub-picosecond, ∼5 ps, and
∼40 ps time scales, which we attribute to scattering from LO-phonons,
contribution from a hot phonon bottleneck effect and Auger heating,
respectively. Thermalization appears also influenced by the FAPbI3 NCs purity, with trapping at unreacted precursor impurities
further reducing the carrier energy loss rate.
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semiconductor NCsLong-Lived Hot CarriersFAPbI 3 NCs puritycarrier energycarrier energy loss rateiodide perovskitephonon bottleneck effectunreacted precursor impurities2 ordersultrafast thermalization processrise timecarrier relaxationFAPbI 3cooling stagesintraband relaxationAuger heatingmetal halide perovskitesIodide Nanocrystalstime scales
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