Compositional Tuning of Carrier Dynamics in Cs2Na1- xAgxBiCl6Double-Perovskite Nanocrystals

Dongxu Zhu, Juliette Zito, Valerio Pinchetti, Zhiya Dang, Andrea Olivati, Lea Pasquale, Aiwei Tang, Matteo L. Zaffalon, Francesco Meinardi, Ivan Infante*, Luca De Trizio*, Liberato Manna*, Sergio Brovelli*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

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.

Original languageEnglish
Pages (from-to)1840-1847
Number of pages8
JournalACS Energy Letters
Volume5
Issue number6
Early online date8 May 2020
DOIs
Publication statusPublished - 12 Jun 2020

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