We devised a hot-injection synthesis to prepare colloidal double-perovskite Cs2NaBiCl6 nanocrystals (NCs). We also examined the effects of replacing Na+ with Ag+ cations by preparing and characterizing Cs2Na1–xAgxBiCl6 alloy NCs with x ranging from 0 to 1. Whereas Cs2NaBiCl6 NCs were not emissive, Cs2Na1–xAgxBiCl6 NCs featured a broad photoluminescence band at ∼690 nm, Stokes-shifted from the respective absorption by ≥1.5 eV. The emission efficiency was maximized for low Ag+ amounts, reaching ∼3% for the Cs2Na0.95Ag0.05BiCl6 composition. Density functional theory calculations coupled with spectroscopic investigations revealed that Cs2Na1–xAgxBiCl6 NCs are characterized by a complex photophysics stemming from the interplay of (i) radiative recombination via trapped excitons localized in spatially connected AgCl6–BiCl6 octahedra; (ii) surface traps, located on undercoordinated surface Bi centers, behaving as phonon-assisted nonradiative decay channels; and (iii) a thermal equilibrium between trapping and detrapping processes. These results offer insights into developing double-perovskite NCs with enhanced optoelectronic efficiency.
Zhu, D., Zito, J., Pinchetti, V., Dang, Z., Olivati, A., Pasquale, L., et al. (2020). Compositional tuning of carrier dynamics in Cs2Na1-xAgxBiCl6 double perovskite nanocrystals. ACS ENERGY LETTERS, 5(6), 1840-1847 [10.1021/acsenergylett.0c00914].
Compositional tuning of carrier dynamics in Cs2Na1-xAgxBiCl6 double perovskite nanocrystals
Valerio Pinchetti;Matteo Luca Zaffalon;Francesco Meinardi;Sergio Brovelli
Ultimo
2020
Abstract
We devised a hot-injection synthesis to prepare colloidal double-perovskite Cs2NaBiCl6 nanocrystals (NCs). We also examined the effects of replacing Na+ with Ag+ cations by preparing and characterizing Cs2Na1–xAgxBiCl6 alloy NCs with x ranging from 0 to 1. Whereas Cs2NaBiCl6 NCs were not emissive, Cs2Na1–xAgxBiCl6 NCs featured a broad photoluminescence band at ∼690 nm, Stokes-shifted from the respective absorption by ≥1.5 eV. The emission efficiency was maximized for low Ag+ amounts, reaching ∼3% for the Cs2Na0.95Ag0.05BiCl6 composition. Density functional theory calculations coupled with spectroscopic investigations revealed that Cs2Na1–xAgxBiCl6 NCs are characterized by a complex photophysics stemming from the interplay of (i) radiative recombination via trapped excitons localized in spatially connected AgCl6–BiCl6 octahedra; (ii) surface traps, located on undercoordinated surface Bi centers, behaving as phonon-assisted nonradiative decay channels; and (iii) a thermal equilibrium between trapping and detrapping processes. These results offer insights into developing double-perovskite NCs with enhanced optoelectronic efficiency.
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