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Title: Is Cs 2 TiBr 6 a promising Pb-free perovskite for solar energy applications?
In a quest for Pb-free perovskites suitable for solar energy applications, Cs 2 TiBr 6 has recently been reported as a promising compound, with appropriate optical and electrical properties as well as high stability under environmental stresses. In this study, we pursue investigation on this compound, demonstrating phase pure Cs 2 TiBr 6 powder formation using solution synthesis and providing complementary experimental characterization and theoretical calculations. An experimental absorption onset of around 2.0 eV is extracted and a weak broad photoluminescence is measured. Density functional theory calculations predict an indirect bandgap, parity-forbidden for both the direct and indirect transitions, which explains the weak and Stokes shifted luminescence. Additionally, we highlight the strong instability of Cs 2 TiBr 6 powder in ambient atmosphere. Therefore, our experimental results supported by theoretical calculations differ from previous results and raise doubts on the suitability of Cs 2 TiBr 6 in its pristine form for solar energy applications.  more » « less
Award ID(s):
1709294
NSF-PAR ID:
10165957
Author(s) / Creator(s):
; ; ; ;
Date Published:
Journal Name:
Journal of Materials Chemistry A
Volume:
8
Issue:
7
ISSN:
2050-7488
Page Range / eLocation ID:
4049 to 4054
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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