Abstract
Recent progress in solar cell and light-emitting devices makes halide perovskite a research hot spot in optics. In this Letter, the nonlinear absorption and fluorescence properties of nanocrystal, one typical organometallic halide perovskite, have been investigated via Z-scan measurements and a density-dependent photoluminescence (PL) spectrum. The nanocrystal exhibits nonlinear absorption under the excitation of 800 nm, whose photon energy is below the bandgap of . The significant absorption is experimentally confirmed to be induced by two-photon absorption (TPA), and the TPA coefficient is measured to be . Moreover, the PL induced by TPA in nanocrystal shows different temperature-dependent behaviors in the range of 90 to 350 K. The peaks of the PL spectrum remain nearly constant at , with a very shallow trough at around 150 K, while a linear blue shift (0.496 meV/K) of the spectrum is observed when temperature is above 160 K. These temperature-dependent fluorescence behaviors can be ascribed to the structural phase transition at about 150 K and the contribution of thermal expansion. Moreover, the exciton binding energy around 160 meV and the optical phonon energy of 15.3 meV are also extracted from the temperature-dependent PL data.
© 2017 Optical Society of America
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