TY - JOUR
T1 - Lead-free cesium titanium bromide double perovskite nanocrystals
AU - Grandhi, G. Krishnamurthy
AU - Matuhina, Anastasia
AU - Liu, Maning
AU - Annurakshita, Shambhavee
AU - Ali-Löytty, Harri
AU - Bautista, Godofredo
AU - Vivo, Paola
N1 - Funding Information:
Funding: This work is part of the Academy of Finland Flagship Programme, Photonics Research and Innovation (PREIN), Decision No. 320165. This work was supported by the Academy of Finland (grant Nos. 326461, 326464). A.M. and P.V. thank the financial support of Tampere University, Faculty of Engineering and Natural Sciences. M.L. thanks the Finnish Cultural Foundation (00210670) for funding. S.A. is grateful to PREIN and Jenny and Antti Wihuri Foundation for the financial support. The authors also acknowledge the support of Jane and Aatos Erkko foundation (project ‘ASPIRE’).
Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2021/6
Y1 - 2021/6
N2 - 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, Cs2 TiBr6, 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 Cs2 TiX6 nanocrystals (X = Br, Cl) and observe tunable morphology and size of the nanocrystals according to the set reaction temperature. The Cs2 TiBr6 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 Cs2 TiBr6 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 Cs2 TiBr6 as well as on other lead-free double perovskites, with stronger focus on currently unexplored nonlinear optical applications.
AB - 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, Cs2 TiBr6, 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 Cs2 TiX6 nanocrystals (X = Br, Cl) and observe tunable morphology and size of the nanocrystals according to the set reaction temperature. The Cs2 TiBr6 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 Cs2 TiBr6 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 Cs2 TiBr6 as well as on other lead-free double perovskites, with stronger focus on currently unexplored nonlinear optical applications.
KW - Double perovskites
KW - Lead-free halide perovskites
KW - Nanocrystals
KW - Nonlinear optics
KW - Stability
KW - Third-harmonic generation
KW - Titanium (Ti)
U2 - 10.3390/nano11061458
DO - 10.3390/nano11061458
M3 - Article
AN - SCOPUS:85107016093
SN - 2079-4991
VL - 11
JO - Nanomaterials
JF - Nanomaterials
IS - 6
M1 - 1458
ER -