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Issue 4, 2018
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Manipulation of cation combinations and configurations of halide double perovskites for solar cell absorbers

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Abstract

Pb-free halide double perovskites, A2B+B3+X6 (A = Cs, B+/B3+ = metal cation, and X = halogen anion), have been proposed to replace hybrid halide perovskites (e.g., CH3NH3PbI3) as stable Pb-free materials for high efficiency solar cell absorbers. Here, using first-principles density functional theory calculations and symmetry analysis we show that the overall electronic properties of A2B+B3+X6 depend strongly on the atomic orbitals and site occupation of the B+ and B3+ cations. For ordered A2B+B3+X6 compounds, in order to have a direct band gap with allowed optical transitions, both of the B+ and B3+ cations should possess the lone-pair s state. Thus, only the A2BIIIA+BVA3+X6 family of compounds satisfies this criterion. On the other hand, we reveal that the electronic structures of A2B+B3+X6 can be greatly tuned by controlling the site occupation ordering parameter of the B+ and B3+ cations. Compared to their ordered counterparts, the band gaps of disordered A2B+B3+X6 alloys can be reduced significantly and the band gap character can be switched from indirect to direct, which greatly expanded the possible candidates for solar cell applications. Our results thus set a new direction and guidelines for the design of Pb-free halide double perovskites for solar cells.

Graphical abstract: Manipulation of cation combinations and configurations of halide double perovskites for solar cell absorbers

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Publication details

The article was received on 04 Nov 2017, accepted on 20 Dec 2017 and first published on 21 Dec 2017


Article type: Paper
DOI: 10.1039/C7TA09713A
Citation: J. Mater. Chem. A, 2018,6, 1809-1815
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    Manipulation of cation combinations and configurations of halide double perovskites for solar cell absorbers

    P. Zhang, J. Yang and S. Wei, J. Mater. Chem. A, 2018, 6, 1809
    DOI: 10.1039/C7TA09713A

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