Perovskites attract attention as efficient light absorbers for solar cells due to their high-power conversion efficiency (up to 24%). The high photoelectric conversion efficiency is greatly affected by a suitable band structure. Cation substitution can be an effective approach to tune the electronic band structure of lead halide perovskites. In this work, superalkali cations were introduced to replace the Cs+ cation in the CsPbBr3 material. The bimetallic superalkalis (LiMg, NaMg, LiCa, and NaCa) were inserted since they are structurally simple systems and have a strong tendency to lose one electron to achieve a closed-shell cation. The cation substitution in the lead halide perovskite leads to changes in the shape of both valence and conduction bands compared to CsPbBr3. Introducing superalkali cations produces extra electronic states close to the Fermi level, which arise from the formation of alkali earth metal states at the top of the valence band. Our first-principles computations reveal that bimetallic superalkali substitution decreases the bandgap of the perovskite. The bandgaps of MgLi–PbBr3 (1.35 eV) and MgNa–PbBr3 (1.06 eV) are lower than the bandgap of CsPbBr3 (2.48 eV) and within the optimal bandgap (i.e., 1.1–1.4 eV) for single-junction solar cells. Thus, the MgLi–PbBr3 and MgNa–PbBr3 inorganic perovskites are promising candidates for high-efficiency solar cells.
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7 November 2021
Research Article|
November 02 2021
Bimetallic superalkali substitution in the CsPbBr3 perovskite: Pseudocubic phases and tunable bandgap
Special Collection:
From Atom-Precise Nanoclusters to Superatom Materials
Celina Sikorska
;
Celina Sikorska
a)
1
The MacDiarmid Institute of Advanced Materials and Nanotechnology, A New Zealand Centre of Research Excellence, Wellington
, New Zealand
2
Department of Physics, The University of Auckland
, Private Bag 92019, Auckland, 1010, New Zealand
a)Author to whom correspondence should be addressed: celina.sikorska@auckland.ac.nz
Search for other works by this author on:
Nicola Gaston
Nicola Gaston
1
The MacDiarmid Institute of Advanced Materials and Nanotechnology, A New Zealand Centre of Research Excellence, Wellington
, New Zealand
2
Department of Physics, The University of Auckland
, Private Bag 92019, Auckland, 1010, New Zealand
Search for other works by this author on:
a)Author to whom correspondence should be addressed: celina.sikorska@auckland.ac.nz
Note: This paper is part of the JCP Special Topic on From Atom-Precise Nanoclusters to Superatom Materials.
J. Chem. Phys. 155, 174307 (2021)
Article history
Received:
August 18 2021
Accepted:
October 15 2021
Citation
Celina Sikorska, Nicola Gaston; Bimetallic superalkali substitution in the CsPbBr3 perovskite: Pseudocubic phases and tunable bandgap. J. Chem. Phys. 7 November 2021; 155 (17): 174307. https://doi.org/10.1063/5.0067708
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