Influence of halide composition on the structural, electronic, and optical properties of mixed CH3NH3Pb(I1xBrx)3 perovskites calculated using the virtual crystal approximation method

Un-Gi Jong, Chol-Jun Yu, Jin-Song Ri, Nam-Hyok Kim, and Guk-Chol Ri
Phys. Rev. B 94, 125139 – Published 21 September 2016

Abstract

Extensive studies have demonstrated the promising capability of the organic-inorganic hybrid halide perovskite CH3NH3PbI3 in solar cells with a high power conversion efficiency exceeding 20%. However, the intrinsic as well as extrinsic instabilities of this material remain the major challenge to the commercialization of perovskite-based solar cells. Mixing halides is expected to resolve this problem. Here, we investigate the effect of chemical substitution in the position of the halogen atom on the structural, electronic, and optical properties of mixed halide perovskites CH3NH3Pb(I1xBrx)3 with a pseudocubic phase using the virtual crystal approximation method within density functional theory. With an increase of Br content x from 0.0 to 1.0, the lattice constant decreases in proportion to x with the function of a(x)=6.4200.333x (Å), while the band gap and the exciton binding energy increase with the quadratic function of Eg(x)=1.542+0.374x+0.185x2 (eV) and the linear function of Eb(x)=0.045+0.057x (eV), respectively. The photoabsorption coefficients are also calculated, showing a blueshift of the absorption onsets for higher Br contents. We calculate the phase decomposition energy of these materials and analyze the electronic charge density difference to estimate the material stability. Based on the calculated results, we suggest that the best match between efficiency and stability can be achieved at x0.2 in CH3NH3Pb(I1xBrx)3 perovskites.

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  • Received 3 June 2016
  • Revised 5 July 2016

DOI:https://doi.org/10.1103/PhysRevB.94.125139

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Un-Gi Jong1, Chol-Jun Yu1,*, Jin-Song Ri1, Nam-Hyok Kim2, and Guk-Chol Ri2

  • 1Department of Computational Materials Design, Faculty of Materials Science, Kim Il Sung University, Ryongnam-Dong, Taesong District, Pyongyang, Democratic People's Republic of Korea
  • 2Department of Theoretical Physics, Faculty of Physics, Kim Il Sung University, Ryongnam-Dong, Taesong District, Pyongyang, Democratic People's Republic of Korea

  • *Corresponding author: ryongnam14@yahoo.com

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Vol. 94, Iss. 12 — 15 September 2016

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