Abstract
Sn doping is established as an effective approach to promote the light emission properties in in two-dimensional lead-halide perovskites. However, the effect on the charge carrier dynamics is largely unexplored. In this work, we conduct terahertz spectroscopy to study the effects of Sn doping on the charge dynamics in the two-dimensional perovskites PEA2SnxPb1–xI4 (PEA = phenethylammonium) with different doping levels. The spectral dispersion analysis suggests that the early-stage dynamics with lifetime of ∼ 2 ps is contributed by both the transport of hot charge carriers and the polarizability of hot excitons. The long-lived component of first-order charge carrier recombination is dramatically improved when Sn doping increases, which is ascribed to the equilibrium between charge carriers and excitons with smaller bind energies in the higher-level Sn-doped samples. The finding in this work suggests Sn doping is an effective approach to optimize the charge carrier transport in 2D perovskite for potential optoelectronic applications.
Highlights
Two-dimensional (2D) lead-halide perovskites have become increasingly prevalent in the past few years due to its high performance in optoelectronics devices with increased stability in ambient condition (Ishihara et al, 1990; Smith et al, 2014; Wang et al, 2016; Yuan et al, 2016; Grancini and Nazeeruddin, 2019; Ke et al, 2019; Blancon et al, 2020)
We study the dynamics of charge carriers in twodimensional perovskites PEA2SnxPb1−xI4 (PEA = phenethyl ammonium) with different level of Sn doping (
We study the dynamics of charge carriers in thin film samples of 2D perovskite PEA2SnxPb1−xI4 with five different doping levels (x = 0%, 0.1%, 1%, 5%, 10%)
Summary
Two-dimensional (2D) lead-halide perovskites have become increasingly prevalent in the past few years due to its high performance in optoelectronics devices with increased stability in ambient condition (Ishihara et al, 1990; Smith et al, 2014; Wang et al, 2016; Yuan et al, 2016; Grancini and Nazeeruddin, 2019; Ke et al, 2019; Blancon et al, 2020). The broadband emission has been assigned to the extrinsic selftrapped excitons (STE) due to efficient electron-phonon coupling and low-dimensionality structure (Hu et al, 2016; Li S. et al, 2019; Li T. et al, 2019; Wang et al, 2019; Li J. et al, 2020) It remains poorly explored how these Sn doping affect the transport of charge carriers in the 2D perovskites. The proportion of long-lived component (∼ 1 ns) is dramatically improved with increasing the level of Sn doping, which can be understood as the equilibrium between the charge carriers and bounded electronhole pairs with reduced binding energy in the samples with higher level Sn doping Such a scenario has been confirmed by temperature-dependent measurements. The finding in this work suggests Sn doping is an effective approach to optimize the charge carrier transport in 2D perovskite for potential optoelectronic applications
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