Lead-Free Cesium Titanium Bromide Double Perovskite Nanocrystals

Autor: G. Krishnamurthy Grandhi, Anastasia Matuhina, Maning Liu, Shambhavee Annurakshita, Harri Ali-Löytty, Godofredo Bautista, Paola Vivo
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Nanomaterials, Vol 11, Iss 6, p 1458 (2021)
Druh dokumentu: article
ISSN: 2079-4991
DOI: 10.3390/nano11061458
Popis: Double perovskites are a promising family of lead-free materials that not only replace lead but also enable new optoelectronic applications beyond photovoltaics. Recently, a titanium (Ti)-based vacancy-ordered double perovskite, Cs2TiBr6, has been reported as an example of truly sustainable and earth-abundant perovskite with controversial results in terms of photoluminescence and environmental stability. Our work looks at this material from a new perspective, i.e., at the nanoscale. We demonstrate the first colloidal synthesis of Cs2TiX6 nanocrystals (X = Br, Cl) and observe tunable morphology and size of the nanocrystals according to the set reaction temperature. The Cs2TiBr6 nanocrystals synthesized at 185 °C show a bandgap of 1.9 eV and are relatively stable up to 8 weeks in suspensions. However, they do not display notable photoluminescence. The centrosymmetric crystal structure of Cs2TiBr6 suggests that this material could enable third-harmonic generation (THG) responses. Indeed, we provide a clear evidence of THG signals detected by the THG microscopy technique. As only a few THG-active halide perovskite materials are known to date and they are all lead-based, our findings promote future research on Cs2TiBr6 as well as on other lead-free double perovskites, with stronger focus on currently unexplored nonlinear optical applications.
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