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Issue 22, 2020
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Elastic and electronic origins of strain stabilized photovoltaic γ-CsPbI3

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All-inorganic cesium lead triiodide (CsPbI3) perovskite has been widely researched due to its outstanding photovoltaic properties. At room temperature, there are two orthorhombic CsPbI3 phases (black γ-CsPbI3 perovskite and yellow δ-CsPbI3 non-perovskite). In this study, these two polymorphic structures have been studied via density functional theory calculations in respect to their electronic and elastic properties. Our calculation results give full mapping of Young's moduli of the γ-CsPbI3 structure for all crystallographic orientations, which reveal that the optimum directions for stabilizing the γ-CsPbI3via strain are approximately along 〈012〉. Moreover, we found that these two polymorphs have distinct stiffness along respective octahedral chains due to their different kinds of octahedral connections. Furthermore, the calculated band structures and density of states disclose that both phases have direct bandgaps, and the bandgap of δ-CsPbI3 is much wider due to its weak Pb 6p–I 5p antibonding coupling in the conduction band and low octahedral connectivity. Our findings provide fundamental elastic and electronic insights which are instructive for strain engineering of photovoltaic γ-CsPbI3.

Graphical abstract: Elastic and electronic origins of strain stabilized photovoltaic γ-CsPbI3

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Article information

27 Mar 2020
21 May 2020
First published
22 May 2020

Phys. Chem. Chem. Phys., 2020,22, 12706-12712
Article type

Elastic and electronic origins of strain stabilized photovoltaic γ-CsPbI3

Z. Li, Y. Qin, L. Dong, K. Li, Y. Qiao and W. Li, Phys. Chem. Chem. Phys., 2020, 22, 12706
DOI: 10.1039/D0CP01649G

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