Abstract
In this work, transient absorption (TA) spectra of lead based organic-inorganic mixed halide (CH3NH3PbI3-xClx) perovskite thin film were investigated under excitation of femto-second pump pulse (400 nm, 60 fs) for various carrier density (1018-1019 cm-3). The ultrafast hot carrier (HC) relaxation dynamics is examined by fitting the high energy tail (1.8-2.0 eV) of bleaching band when pumping (~2.63 eV) above the perovskite band-gap (~1.6 eV). It shows that HCs cool down via electron-LO phonon emission over ~800 fs. However cooling is slows down due to delayed relaxation of LO phonon into acoustic phonon in ~11 ps and shows “photon bottleneck” at higher carrier injection density. Further, the decay dynamics of band limited bleaching peak signal around 1.69 eV (730 nm) obtained from TA spectra is well studied to predict the rate constant of radiative recombination. The results shows radiative recombination rate of 10-11 cm-3s-1 and effective diffusion length of ~10 μm in mixed halide perovskite.
Published Version
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