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Electronic Structure and Trap States of Two-Dimensional Ruddlesden–Popper Perovskites with the Relaxed Goldschmidt Tolerance Factor

Liang, Mingli ; Lin, Weihua LU ; Lan, Zhenyun ; Meng, Jie ; Zhao, Qian ; Zou, Xianshao LU ; Castelli, Ivano E. ; Pullerits, Tönu LU ; Canton, Sophie E. LU and Zheng, Kaibo LU (2020) In ACS Applied Electronic Materials 2(5). p.1402-1412
Abstract
Two-dimensional Ruddlesden–Popper perovskites (2D RPPs) have been considered as promising building blocks for optoelectronic applications owing to optical properties comparable to the ones of 3D perovskites, together with superior stability. In addition, the more flexible structure adopted by such perovskites leads to a relaxation of the Goldschmidt tolerance factor (τ) requirement. Herein, we compare the crystalline and electronic structures, as well as the photophysics of two 2D perovskite single crystals (n-BA)2(MA)2Pb3I10 (BMAPI) and (n-BA)2(EA)2Pb3I10 (BEAPI) (n-BA = n-butylamine) containing small A-cations (MA, methylammonium) and large A-cations (EA, ethylammonium), respectively. The latter presents a relaxed τ (τEA > 1) compared... (More)
Two-dimensional Ruddlesden–Popper perovskites (2D RPPs) have been considered as promising building blocks for optoelectronic applications owing to optical properties comparable to the ones of 3D perovskites, together with superior stability. In addition, the more flexible structure adopted by such perovskites leads to a relaxation of the Goldschmidt tolerance factor (τ) requirement. Herein, we compare the crystalline and electronic structures, as well as the photophysics of two 2D perovskite single crystals (n-BA)2(MA)2Pb3I10 (BMAPI) and (n-BA)2(EA)2Pb3I10 (BEAPI) (n-BA = n-butylamine) containing small A-cations (MA, methylammonium) and large A-cations (EA, ethylammonium), respectively. The latter presents a relaxed τ (τEA > 1) compared with the requirement of a stable phase in 3D perovskites (τ < 1). Such relaxed τ is beneficial from the structural flexibility of the long organic cation bilayer and the pronounced lattice distortions in the 2D perovskite structures. We further elucidate how the greater lattice distortions concurrently modulate the electronic structure as well as trap densities in these 2D RPPs. The electronic band gap (Eg) of BEAPI (2.08 ± 0.03 eV) is ∼0.17 eV larger than the one of BMAPI (1.91 ± 0.03 eV). This is mainly because of a shift in the valence band maximum associated with the expansion of the Pb–I bond length in BEAPI. In addition, the overall trap state densities for BMAPI and BEAPI are calculated to be ∼2.18 × 1016 and ∼3.76 × 1016 cm–3, respectively, as extracted from the time-resolved photoluminescence studies. The larger trap density in BEAPI can be attributed to the stronger interfacial lattice distortion that sets in when large EA cations are contained into the inorganic crystal lattice. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
ACS Applied Electronic Materials
volume
2
issue
5
pages
1402 - 1412
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85087612057
ISSN
2637-6113
DOI
10.1021/acsaelm.0c00179
language
English
LU publication?
yes
id
879e444a-9eff-4d77-861b-474f469db657
date added to LUP
2021-02-05 13:01:09
date last changed
2023-11-20 22:31:10
@article{879e444a-9eff-4d77-861b-474f469db657,
  abstract     = {{Two-dimensional Ruddlesden–Popper perovskites (2D RPPs) have been considered as promising building blocks for optoelectronic applications owing to optical properties comparable to the ones of 3D perovskites, together with superior stability. In addition, the more flexible structure adopted by such perovskites leads to a relaxation of the Goldschmidt tolerance factor (τ) requirement. Herein, we compare the crystalline and electronic structures, as well as the photophysics of two 2D perovskite single crystals (n-BA)2(MA)2Pb3I10 (BMAPI) and (n-BA)2(EA)2Pb3I10 (BEAPI) (n-BA = n-butylamine) containing small A-cations (MA, methylammonium) and large A-cations (EA, ethylammonium), respectively. The latter presents a relaxed τ (τEA &gt; 1) compared with the requirement of a stable phase in 3D perovskites (τ &lt; 1). Such relaxed τ is beneficial from the structural flexibility of the long organic cation bilayer and the pronounced lattice distortions in the 2D perovskite structures. We further elucidate how the greater lattice distortions concurrently modulate the electronic structure as well as trap densities in these 2D RPPs. The electronic band gap (Eg) of BEAPI (2.08 ± 0.03 eV) is ∼0.17 eV larger than the one of BMAPI (1.91 ± 0.03 eV). This is mainly because of a shift in the valence band maximum associated with the expansion of the Pb–I bond length in BEAPI. In addition, the overall trap state densities for BMAPI and BEAPI are calculated to be ∼2.18 × 1016 and ∼3.76 × 1016 cm–3, respectively, as extracted from the time-resolved photoluminescence studies. The larger trap density in BEAPI can be attributed to the stronger interfacial lattice distortion that sets in when large EA cations are contained into the inorganic crystal lattice.}},
  author       = {{Liang, Mingli and Lin, Weihua and Lan, Zhenyun and Meng, Jie and Zhao, Qian and Zou, Xianshao and Castelli, Ivano E. and Pullerits, Tönu and Canton, Sophie E. and Zheng, Kaibo}},
  issn         = {{2637-6113}},
  language     = {{eng}},
  number       = {{5}},
  pages        = {{1402--1412}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{ACS Applied Electronic Materials}},
  title        = {{Electronic Structure and Trap States of Two-Dimensional Ruddlesden–Popper Perovskites with the Relaxed Goldschmidt Tolerance Factor}},
  url          = {{http://dx.doi.org/10.1021/acsaelm.0c00179}},
  doi          = {{10.1021/acsaelm.0c00179}},
  volume       = {{2}},
  year         = {{2020}},
}