CC BY
9ALT'22
LM-P-3
LASER-MATTER INTERACTION
Influence of Multi-Photon Laser Excitation on Excitons and Free Charge Carriers Dynamics in Lead-Halide Perovskites
Lead halide perovskites are widely known as exciton materials, however, the interplay of excitons and free carriers in them strongly depends on the concentration of charge carriers, temperature, and exciton Bohr radius [1]. The competition between the contributions of excitons and free carriers largely determines the nature of various photophysical processes. It was proved that the contribution of free carriers dominates in solar cells [2], but excitons dominates in light-emitting devices [3]. However, when the carrier concentration becomes extremely high in processes such as lasing [4] and nonlinear upconversion [5], identifying the dominant mechanism becomes a multifactorial problem relevant for modern nanophotonics.
Here the results of a comprehensive study of linear and nonlinear photoluminescence (PL) in CsPbBr3 perovskites depending on the incident excitation energy, temperature, and size of the perovskite structure are presented. It is shown that the dependence of the PL quantum yield on the incident radiation wavelength demonstrates pronounced transitions between different orders of nonlinearity and dependence of output emission intensity on input intensity reveals spectral ranges in which the order of nonlinearity is not equal to the number of photons required for interband absorption. In turn, in the temperature range from 300 K to 6 K, the dependence of the PL on the intensity of the incident radiation shows a decrease in the order of nonlinearity, which corresponds to the exciton response. A similar effect is observed for the case of reduction of the perovskite structures sizes from a 70 nm thick polycrystalline film to nanocrystals (NCs) of 10 nm in diameter. The results obtained are useful for nonlinear nanophotonics, in particular, it is shown that CsPbBr3 NCs introduced in resonant CaCO3 microspheres exhibit two-fold enhanced two-photon PL, which is consistent with the quadratic dependence of the PL signal on the incident light intensity for NCs.
This research was supported by the Presidential Scholarship for Young Scientists and Postgraduates (SP-5169.2021.5) and Priority 2030 Federal Academic Leadership Program Project №922011.
References:
[1] Stranks, S. D, et.al. (2014) Physical Review Applied, 2(3), 034007.
[2] Green, M. A, et.al. (2014) Nature photonics, 8(7), 506-514.
[3] Kim, Y.H., et.al. (2016) PNAS, 113(42), 11694-11702.
[4] D. Yang, et.al. (2018) Optical Letters, 43, 2066.
[5] Zhu, X., et.al. (2019) Advanced Materials, 31(49), 1901240.
D.I. Markina, P.A. Tonkaev, M.A. Masharin, A.P.Pushkarev, S.V. Makarov
ITMO University, Kronverkskypr., 49, St. Petersburg, 197101 Main author email address: daria.markina@metalab.ifmo.ru
